
Clih 



E L E M li: N T S 



OF 



CHEMISTRY; 



IN WHICH THE 



RECENT DISCOVERIES IN THE SCIENCE ARE INCLUDED 



DOCTRINES FAMILIARLY EXPLAINED, 



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Mom. Con. M. S. R. i. iv ic ■ lior of Notes to Conv. on Chemistry 

Author o^ trv „ . r. Mineralogy; of Nat History 

ofC ^^'jyiiL Natural Philosophy, &C. 

of At^tro' 
I j'wemy-ninth cdir on. 



PUBLISHED BY ROBINSON, PRATT, & CO. 

NO. 63 WALL strejst; 

4ND 8OE1D BT THE PRINCIPAL B00K8ELLKR9 /i^BROVOBOUT 
THI UNITED STATIi. 



1839. 






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"I y, In which the rea?nt Discoveries in the Science are induileil, 

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r • r -- • s. By J. I* Ct>m8tock, M. 1). Mem. Con. M. ?^. ; 

H ^; K I ^l - \ N .■e« to C<mv. on Chem. ; Author of (Jram. Chem. ; 

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CHARLES A. INGE^ROU., 
Qltrk of the District of Cim»^cticu . 



Git 
MfB.ThomftH 1- 



PREFACE 



It is hardly necessary for the author of the following volume 
to make any excuses for its publication, since, notwithstanding 
the multiplicity of books on the same subject, there seems to be 
none, which are exactly adapted to the object for which this is 
principally designed. The Conversations on Chemistry, and the 
works of Parke and Joyce, besides the interlocutory form in which 
they are written, are objectionable, in not containing the recent 
discoveries and improvements in the science 5 and the volume of 
Dr. Turner, though free from these objections, is too large for the 
use of schools and academies. 

In this volume, it has been the intention of the author, not only 
to avoid these objections, but, at the same time, to explain the 
elements and doctrines of the science in sufficient detail, to give 
a competent knowledge of its several parts, and in such language 
as can be understood by those who will but read the book atten- 
tively and pursue the subject in course. 

It appears to the writer, that in teaching Chemistry to youth, 
ite elementary parts have not been sufficiently insisted on at the 
beginning. Of all the sciences, this is the most complete, in 
respect to its language — the order of its arrangement, the succes- 
sion of its subjects, and consequently in the facility with which 
it may be learned. But from these perfections, arises the abso- 
lute necessity of becoming well acquainted with its first principles, 
before the student ' "^e and retain any useful knowledge 

from its study. T- - iclature of chemistry, the laws of 

affinity, and the doctr - roportions, are far more necessary to 
a proper knowledge ot tins cience, than is a knowledge of ma 
thematics to the study of Astronomy. The cause of an eclipse, 
or the reason why the complicated motions of the earth shonx 
produce a change of seasons, can be fully understood without the 
use of mathematics. But without a knowledge of affinity, and 
proportions, the decomposition of a salt, or the formation of a de- 
finite compound, are absolutely incomprehensible phenomena; 
nor can they be explained without a previous acquaintance with 
the peculiar language of chemistry. 

It is from a conviction of the importance of first principles ui 
learning this science, that the author has devoted so much atten- 
tion to the imponderable agents, attraction, affinity, and galvanism, 
and to the explanation of definite proportions and chemical equi- 
valents. 



4 FRBFACK. 

Tho doclrine of definite proportions, being now universally 
adopted, forms one of the lundainental principles of cliemical 
science. And whether the theory of atoms, whicli accounts for 
the facts on whicli this doctrine is founded, be true, or false, the 
doctrine itself will ever maintain its integrity, its elements being 
nothing more than the expression of facts wnich experiment and 
analysis have developed. The subject of proportions, indepen- 
dently of its relation to the theory or practice of Chemistry, is 
hii^^hly curious and of uncommon interest, both to the naturalist 
and the moral philosopher. To the first it shows that the laws 
of nature are ajually inherent and eflicient, in dead and in ani- 
mated matter, and that the ellects of these laws are as peculiar 
and distinctive in the formation of chemical compounds, as they 
are in t)ie proiluction and habitudes of the dilferent races of ani- 
mals. To the moralist, this subject teaches, that nothing has 
been formed by the fortuitous concurrence of atoms, but that even 
the "stocks and stones" bear the impress of creative agency and 
design — that the air he breathes and the water he drinks, are 
formed of invariable proportions of certain elements, and thai 
these compounds are so j)recisely adapted to liis nature and 
wants, that the least change in the proportion of their constituents 
would inevitably effect his destruction. 

Besides the charms which this subject presents to the reflecting 
student, tiie composition of compound bodies, in recent books of 
chemistry, is expressed in equivalent numbers, and therefore 
cannot be understood without a knowledge of the doctrine of 
proportions. The author, therefore, before the description of each 
element and compound, lias atfixed to its name, at the head of the 
sections, its combining number, or atomic -weight. By this ar 
rangement, the pupil, at a siui^le glance, becomes acquainted, not 
only with tlie scientific, and common names, but also Avith the 
composition, and proportions of all the compounds described. 

In respect to the authorities which ' ^ve been consulted in the 
composition of this work, the prin< 3r. Thomson, Dr. 

Henry, Sir II. Davy, Mr. Gray, Dr.\ .. Accum, Mr. Fara- 

day, the Library of llseful Knowledf ... Journal of the Royal 
Institution, Silliman's Journal, and jJr. Turner. 

Of the work of tJie latter author, free use has been made, bis 
arrangement of subjects, with some variations, having been adopt- 
ed, and his exposition of the doctrine of proportions carefully 
consulted. Tlie work now offered, is not however to be considered 
as a servile compilation; the former experience of the author as 
a lecturer, and his habit, for many years, of analysing various 
substances, having given him opportunities, not only of verifying 
the deducti()ns of others, but occasionally of making new experi- 
ments for himself. 

Hartford, November 15, 1831. 



CONTENTS. 





PART L 




^PDNDERABLE AgENTS - 


. 10 


Single elective aflSnity - 


73 


<^aloric - - - - 


11 


Double elective affinity 


74 


Combined caloric - - - 


13 


Cohesion - - - - 


76 


Steam - - - - 


15 


Ctuantity of matter 


77 


Evaporation - - - - 


18 


Gravity - - - - 


79 


Conductors of caloric 


22 


Changes produced by chemical 




Expansive pov^er of heat 


25 


combinations - - - 


79 


Specific caloric - - - 


32 


Force of chemical affinity 


83 


Thermometer - - - 


35 


Indefinite proportions 


84 


Cold - - . . 


39 


Definite proportions 


86 


Sources of caloric - - - 


41 


Combination by volumes - 


91 


Light - - . - 


44 


Chemical equivalents 


93 


Phosphorescence - - - 


45 


Method of ascertaining the pro- 




Electricity - - - 


48 


portional numbers 


95 


Chemical effects of electricity- 


53 


WoUaston's scale 


96 


Galvanism _ - - 


54 


Theory of atoms - - - 


98 


Chemical effects of galvanism 


61 


Chemical apparatus - 


100 


Heating effects of galvanism 


68 


Gas apparatus - - - 


104 


Attraction - - - - 


69 


Lamp furnace - - - 


106 


Chemical attraction - 


70 


Portable balance - - - 


107 


AflEinity - - . - 


71 


Specific gravity - - - 


107 


Simple affinity - . -. 


72 


Nomenclature - - . 


110 


PART 11. 




Ponderable Bodies 


112 


Nitrogen and oxygen - 


138 


Explanations - - - 


112 


Nitrous oxide - . . 


138 


Inorganic chemistry 


115 


Nitric oxide - - - 


141 


Non-metallic substances - 


115 


Nitrous acid - - - 


143 


Oxygen - - , - 


115 


Nitric acid - - • 


144 


Hydrogen 


122 


Nitrogen and hydrogen 


146 


Water - - . - • 


127 


Ammonia - - - 


146 


Compound blow-p^ 


129 


Carbon- - - . - 


147 


Properties of water 


131 


Carbon and oxygen - 


149 


Oxygenized water - 


133 


Sulphur - - • 


154 


Nitrogen - - - - 


134 


Sulphur and oxygen 


155 


The atmosphere 
1* 


135 


Phosphorus - - • - 


160 



CHEMISTRY. 



Chemistry is that science which investigates the compo- 
sition and properties of bodies, and by which we are enabled 
to explain the causes of the natural changes which take place 
in material eubstances. 

Natural Science has been divided into two great branches, 
the one comprehending all those natural changes which are 
accompanied by sensible motions ; the other, including all 
those natural changes accompanied by insensible motions. 
The first science is called Natural Philosophy ; including 
also the Philosophy of Mechanics, and the laws of motion. 
The second is known under the name of Chemistry, or Che- 
mical Philosophy. 

As a science, Chemistry is of the highest importance to 
mankind, since by its investigations, the practical arts are 
constantly improving. 

All chemical knowledge is founded on analysis and synthe- 
sis, that is, the decomposition of bodies, or the separation of 
compounds into their simple elements, or the recomposition 
of simple bodies into compounds. 

When w^ater is passed through a red hot iron tube, in the 
form of steam, it is decomposed ; its oxygen uniting with the 
iron, while its hydrogen passes away in a state of freedom, or 
may be collected and retained. This is called analysis ; and 
the bodies so separated from each other, if they cannot again 
be decomposed, are called elements. Thus hydrogen and 
oxygen are the elements of water. When oxygen, which 
may be obtained pure, as will be seen in another place, is 
burned with hydrogen, a quantity of water will be formed. 
This is called synthesis, or the recomposition of water from 
its elements. Thus all knowledge of this science is obtainea 
by experiment. 

What is Chemistry 1 How is icience divided? What is the foundation of allijheinl* 
Ca] knowledge ? What is analysis 2 What is synthesis % 



10 IMPONDERABLE AGENTS. 

As a science, chemistry is intimatelv connected with a 
great variety of natural phenomena. All satisfactory expla- 
nation of tlie causes of rain, hail, dew, wind, earthquakes, 
and volcanoes, have been given by the aid of chemical 
knowledi^e. The phenomena of respiration, the decay and 
o-rowth of plants, and the functions of the several parts of 
animals, are also explained in a satisfactory manner, only 
by the aid of chemistry. 

As an art, chemistry is connected, more or less intimately 
with nearly every branch of human industry, and particular- 
ly wiili agriculture and manufactures. In its application to 
agriculture, chemi.stry furnishes the most direct and certain 
means of ascertain inc^ what a barren soil wants to make it a 
fruitful one, and also what ini^fredient any soil requires to 
bt^st adapt it to any given kind of produce. Many of our most 
common and useful articles are manufactured entirely by 
chemical processes. The making of soap, glass, bleaching 
aalts, the several kinds of acids, and almost every kind oi 
medicine, depend wholly on the manipulations of chemistry. 
The art of the potter, iron-smith, tanner, sugar-maker, dis- 
tiller, brewer, vinter, paper-maker, and painter, are also con- 
nected in various degrees with chemistry. 

Natural objects may be separated into two great di\^sion£, 
or classes, viz. ; Imponderable agents and Ponderable bodies 



PART I. 



IMPONDERABLE AGENTS. 



The imponderjible agents are Light, Caloric, or Heat, 
Klectricity, and (Jalvanism. These are called the imponde- 
rable agents, because they possess no appreciable weight, 
I'he investigation of many of the properties of these agents, 
and particularly those of light and attraction, belong to the 
several departments of Natural Philosophy, but they each 
p().ssrss properties also, which are strictly chemical, and it is 
these properties only, which it is proposed here to examine. 

Whnl are among ihc natural phenomena which clieniisiry exjilainsl What are 
among the mcwi iniiwrjnt ana which ilerive ndvaniagc from chcmi^iry 1 How are nniu- 
ral objecu divided 1 Wliai are the Imponderable agcnia "» Wliy are theae agents called 
Unpoodmbltl 



CALORIC. 11 



CALORIC. 

Heat is the sensation which one feels when he touches a 
J)ody hotter than the hand ; and this sensation is caused by 
the passage of caloric from the hot body to the hand. Thus 
caloric is the cause of the sensation which we call heat, and 
heat is the effect of the passage of caloric into the hand. 
Caloric, then, is the matter, or principle of heat, while heat is 
the sensation produced by the transfer of this principle to the 
living system, from some body hotter than itself 

Caloric is imponderable ; that is, there is no appreciable 
difference in the weight of a body, whether it is hot or cold. 

This principle seems to be present in all bodies, nor is there 
any known process by w^hich it can be separated from any 
substance. For since heat constantly passes from the hotter 
to the colder body, until every thing in the same vicinity 
becomes of an equal temperature, so if we take a substance at 
a temperature however low, and carry it to a place where the 
temperature is still lower, this substance will give out heat 
until its temperature becomes the same with that of the sur- 
rounding air. For instance, if a piece of ice at 32 degrees 
of temperature, could be transported to any place, as in Si- 
beria, where the temperature is 60 degrees below 32, then 
this piece of ice will continue to emit caloric until its tempe- 
rature becomes only equal to that of the surrounding atmos- 
phere, and it would therefore give out 60 degrees of heat. 
It will be quite obvious to any one, that if a piece of iron, or 
any other substance, be carried from the open air on a sum- 
mer's day, where the heat is 92, to an ice house, where the 
heat is only 32, that the iron will continue to part with its 
heat until it becomes of the same temperature with the ice, 
and therefore that it will in a short time, lose 60 degrees of 
heat, as indicated by the thermometer. 

Heat and cold are therefore merely relative terms, and so 
far as our sensations are concerned, depend on circumstan- 
ces. Thus we call a body cold when its temperature is lower 
than our own, and it has at the same time, the power of con- 
ducting heat rapidly. That the sensation of cold, which we 

When one touches a body hotter than his hand, why does he feel the sensation of heatl 
What is caloric 1 What is heat 1 How is it proved that caloric is imponderable 1 
How is it shown that caloric is present in all bodies 1 What illustrations show that ice 
will emit caloric 1 How are heat and cold relative terms 7 How is it shown that the sen* 
«ation of cold often depends on the conducting power of the body % 



12 CALORIC. 

experience, when toucliing anothei' body with tlie hand, de- 
pends greatly on the conducting power of the body touched, 
is easily proved by the following experiment. A piece of 
woollen cloth, or fur, and a vessel of quicksilver, being 
phiced in the same room, will both indicate the same tempera* 
ture, when tlie bulb of a thermometer is wrapped in the one, 
or plunged into the other. And yet if the experiment b^ 
made in the warmest day of summer, the mercury will feel 
cold to the hand, while no sensation will be produced on 
touching the cloth or fur. Now both articles touched, being 
of the same temperature, it is certain that the different .sen- 
sations must depend on the power of the mercury to absorb, 
or conduct away the heat of the hand more rapidly than the 
fur or cloth. 

On the contrary, we say a body is warm, or hot, when it 
imparts heat to the hand, more or less rapidly. But this sen- 
sation, to a certain degree, also depends on circumstances, 
and is connected with the relative temperature of the hand, 
and the conducting power of the substance touched. Thus 
if one hand be placed in water, at 32 degrees, and the other 
in water at 130 degrees, and then both hands be plunged 
into water at 90 degrees, one hand will feel cold, and the 
other warm, though the temperature to which both are expo- 
sed is the same. This principle is illustrated by the differ- 
ent sensations which men and animals experience, when 
transported from a cold or hot climate, to one which is tem- 
perate. A Russian would consider the coldest New England 
winter, a pleasant and comfortable season, while an inhabi- 
tant of Sumatra, or Borneo, would tremble with the cold of 
our September. A Avhite bear from Greenland, or a dog from 
Kamtschatka, would constantly sufferfrom the heat, while an 
elephant, or a naked dog from Africa, would require protec- 
tion from the cold. 

One of the most obvious properties of caloric, is, its ten- 
dency to an cquUibrium, that is, its disposition to pass from the 
hotter body to that which is colder. Thus if several bodies 
of different temperatures be placed in the same room, the 
'varmer body will continue to impart its heat to those which 
aro colder until they all indicate the same temperature by 



When do we say a boi^y is warm or liotl How is it sliown that the sensations of he«i 
and cold dci>ond on cireuinsi^mccs? What illustrations are given of this principle 7 
What is one of the most obvious properties of caloric 1 Wliat is meant by cquilibriura7 
How is it shown that caloric tend.-' to an equilibrium 1 



CALORIC. 13 

the thermometer. This distribution is so equal and general, 
that two thermometers, graduated exactly alike, and placed 
under the same circumstances in the open air, will indicate 
the same degrees of heat though placed miles apart. Thus 
coloric has the power of pervading all substances, and of 
equalizing their temperatures. 

Caloric exists in two different states, viz. in a state of com- 
bination, and in a state of freedom. It has already been 
stated, that all bodies are supposed to contain caloric, but tha 
all bodies do not contain sensible heat, or are not warm to 
the touch requires no proof. Common occurrences, however, 
as we have already seen, are sufficient to show, that to a cer- 
tain extent, the sensation of heat depends on circumstances, 
and that it is only necessary that a body touched, should be 
of a higher temperature than the hand, for us to perceive the 
sensation of warmth. But it by no means proves, that 
because the thing touched does not feel warm, that it con- 
tains no caloric. It follows, therefore, that when the body 
touched, conveys the sensation of heat, that caloric passes 
from the body to the hand, and this is called free, or uncom- 
bined caloric; but that when no sensation follows, the heat 
is combined, or latent, in the body touched, and therefore is 
not imparted to the hand. 

Combined or latent Caloric. This is also sometimes called 
caloric of fluidity, because in the conversion of solids into 
fluids, a quantity of heat is absorbed which is not indicated 
by the thermometer, and which, therefore, becomes latent in 
the fluid. 

The experiments of Dr. Black, in relation to this subject, 
are highly curious and interesting. These experiments 
prove, that if a pound of water at 32 degrees be mixed with 
a pound of water at 172 degrees, the temperature of the 
mixture will be intermediate between them, and therefore 
102 degrees. But if a pound of ice at 32 degrees be mixed 
with a pound of water at 172 degrees, the ice will soon be 
dissolved, and then on applying the thermometer to the water 
thus formed, it will be found at the same temperature that 
the ice was before the addition of the warm water, and there 



What conCiUsioa«' is drawn from the fact that caloric is equally distributed? What 
are the two states in which caloric exists 7 Is it a proof that a body contains no 
heat because it does not feel warm? If every body contains heat, why does it not always 
feel warm 1 What is free heat? What is latent heat? How many de^sreesof heat 
oecome latent during the conversion of ice into water ? 

2 



i4 CALORIC. 

fore at 32 degrees instead of 102 degrees, as before. In 
this experiment, therefore, the pound of hot water lost 140 
degrees of caloric which is employed in melting the ice, and 
which is not appreciable by the thermometer, but remains 
latent in the water. It follow, then, that a quantity of ca- 
loric becomes insensible during the melting of ice, v/hich, 
were it free, or uncombined, would raise the temperature ol 
ihe same weight of water 140 degrees; for, the ice being at 
32 degrees, and the water at 172 degrees at the beginning oJ 
the experiment, and the whole being at 32 degrees at the 
end, the water loses MO degrees, being the excess of 172 
degrees above 32. 

It is well known that if a piece of ice be exposed to the 
rays of the hottest sun in the summer, or if it is placed in a 
vessel over a fire, the temperature of the ice, or of the wa- 
ter flowing from it, will not be raised above 32 degrees, until 
the ice is all melted, when the thermometer placed in the ves- 
sel will in:>tantly bejifin to rise. Those who have melted 
snow, or ice for culinary or other purposes, are well aware 
how much more time and fuel it takes to obtain a vessel of 
])oiling water from ice, than it does from the liquid itself. 
But this fact is readily accounted for by Dr. Black's experi- 
ment, since we have seen above, that 140 degrees of heat 
~-'^ first employed merely in converting the ice into water, 
and that this caloric does not raise the water one degree 
above the freezing point, or 32 degrees, until all the ice is 
melted. 

This principle is of vast consequence to the world, and par- 
lic.ularly to the inhabitants of cold climates, where the ground 
\ti covered with snow and ice, a part or the whole of the vear. 
In some northern climates, and particularly in Russia, the 
transition from the cold of winter to the heat of summer, takes 
place within a few days, the ground being covered several 
feet deep with the accumulated snow of the winter. Now 
were it not for the fact above explained, and did the snow and 
ice follow the same law in respect to temperature, that we 
observe in some other bodies, this whole mass would be turned 
into water nearly as soon as the temperature of the atmos- 



How IB ihia shown by cxperimcnll What common fad shows that the tem^wrature 
of water cannot l»c raiftctl as long as it contains ice 1 Wliat cirounisuinccs are meniionco 
tmticr which the great (juaniiiy of caloric aljworbcd by meliinj^ ice, is a blessing to ma/v 
kind 7 When the tcniiKraiuro of ilic aimoHphcre is above the freezing point, why due* 
DOI \he snow a/ul ice instojiUy return to v^atcr? 



STEAM. 15 

phere became above 32 degrees, and consequently the whole 
country would be inundated and destroyed by the flood. 

But in consequence of the quantity of caloric employed in 
the liquefoction of the snow, the melting is gradual, and no 
such accident ensues. This is a striking instance of the 
wisdom and mercy of Providence towards man, though to 
most of the world it is unseen and unknown. 

We have mentioned the melting of ice, as being the most 
familiar example, in most parts of our country, of the con- 
version of a solid into a fluid. But the same principle holds 
with respect to the conversion of other solids into liquids, 
though the quantity of caloric required for this purpose varies 
with the substance. " 

From the experiments of Dr. Irvine, it appears that the fol- 
lowing named substances vary in this respect very widely, 
and also very unexpectedly. Equal weights of each substance 
are supposed to be employed in the experiments : The de- 
grees indicate the extent to which each would have been 
heated by the caloric of fluidity, proper to it. Spermaceti 
145 degrees; Lead 162 deg. ; Bees-Avax 175 deg. ; Zinc 493 
deg. ; Tin 500 deg. ; Bismuth 550 deg. 

Steam. 

When water, or other liquids, are converted into steam, a 
large quantity of daloric is absorbed, which is not indicated 
by the thermometer, and which therefore becomes latent in 
the steam. 

If a thermometer be placed in an open vessel of water, over 
a fire, there will be indicated a gradual increase of heat until 
ihe water boils, after which, no increase of the fire will raise 
me temperature of the water another degree ; nor does the 
tfteam, arising from a vessel of water which boils violently, 
indicate a greater degree of heat than the water itself, or of 
the steam arising from another vessel which boils moderately. 
The steam conveys away all the heat above 212 degrees of 
Fahrenheit's thermometer, which is the temperature of boil- 
ing water under the ordinary pressure of the atmosphere. 

The quantity of caloric which combines with the water to 
form steam, is nearly 1000 degrees greater than that of the 
same weight of boiling water. In other terms, the caloric of 
fluidity in steam surpasses that of an equal weight of boiling 
water by nearly 1000 degrees. Consequently there is nearly 

In melting, do other solids besides ice absorb a qiiantity of caloric not appr-^ciable by 
the thermometer 1 Why cannot water in an open vessel be heated higher than 2i2 de- 
grees 1 How many degrees of heat does steam contain, which is not indicated by the 
thermometer % 



,6 STEAM. 

1000 (lecrrees of hoai in steam which is not indicated by th« 
ihennomt'ter, and is therefore latent. 

Various methods have been adopted by different philoso- 
phers in order to ascertain corn^clly the exact quantity of la- 
tent heat in steam. Amongf these, one of the latest and most 
simple is that of Dr. Ure, of Glasgow. His apparatus con- 
sisted of a small glass retort, with a short neck, inserted into 
a globular receiver of the same material, made very thin, and 
about tliree inches in diameter. This globe was surrounded 
with a certain (juantity of water, at a known temperature, in 
a glass basin. A quantity of water, or other liquid to be ex- 
amined, amounting to 200 grains, was put into the retort, and 
rapidly distilled into the globe, by the heat of an Argand lamp. 
The heat imparted by the condensation of the steam in the 
globe, to the water contained in the dish, by which it was 
surrounded, was indicated by a very delicate thermometer 
kept constantly movinir through it. By means of this contri- 
vance, Dr. Ure found the latent heat of the steam of water to 
be 1000 degrees. That of alcohol, of the sp. grav. 825, to 
be 457, and that of ether about 303. 

We have stated that the temperature of boiling w^ater, and 
of steam, is 212 degrees, under the ordinary pressure of the 
atmosphere. The cause of ebullition, or boiling, is the form- 
ation of vapor, or steam, at the bottom of the vessel, in con- 
se(|uence of the applhcation of heat there. The steam being 
lighter than the water, or other fluid from which it is made, 
constantly ascends in bubbles, and escapes from the surface 
into the open air. The process of boiling, when conducted 
in a tall glass vessel, over an Argand lamp, may be minutely 
examined, and is both interesting and instructive. 

It is found by experiment, that different fluids at the surface 
of the earth boil at different temperatures, depending gene- 
rally on the sjH^ciflc gravity of the fluid, and also, that the 
same fluid boils at various temperatures, depending on the 
degrees of atmospheric pressure. Thus, under the same 
pressure of the atmosphere, or on the level of the sea, water 
l»oils at 212 degrees. Ether at 100 degrees, alcohol 173 de- 
grees, nitric acid, of the specific gravity of 1450, at 240 de- 
grees, and water, saturated with sea salt, 210 degrees. 

We may observe, that in these instances, the boiling of a 

nr«friJ>c thr npp.nmtnn of I>r. Vri*, lo apcrrtnin the qunmity of caloric in Ftrnm 1 
Whai i« liio caujic of cliullition or hoilint; 7 On wliai (Icjtb the Njilmij tcmpi'rature of fluids 
fonernllr doiiend 7 ^''7 •" ^^® boilirtg leniperaiure of wator Miuratwl with salt, higher 
rnaji thai of purr water f Wliai is said concerning iho inljucnce of siwciflc grariiy oo 

Uio boihiig icis|x:ni'.urc ol /iqiiids') 



STEAM. 17 

fluid seems to follow a general law depending' on its specific 
gravity. This is strictly the case in respect to the boiling 
point of sulphuric acid, w^hich always requires a temperature 
for its ebullition in a direct proportion to its specific gravity. 
Thus, according to Dr. Dalton, sulphuric acid sp. gr. 1,408, 
boiled at 240 degrees, while that of sp. gr. 1,670 boiled at 
360 degrees; that of 1,780, at 435 degrees, and that of 1,850 
at 620 degrees. 

The boiling point of a fluid is not, however, in all cases, 
to be estimated by its specific gravity, the fixed oils requiring 
much higher temperatures for their ebullition than other 
fluids of the same density. Thus, linseed oil boils at 640 de- 
grees, though its specific gravity is less than that of water, 
and mercury boils at about 660, though its specific gravity is 
about 1 4 times that of water. 

That w^ater, or any other fluid, will boil with a less degree 
of heat, in proportion as the weight of the atmosphere is re- 
moved, may be readily proved by means of the air pump, or 
by ascending up a mountain, where the air is less dense than 
it is on the level of the sea. 

The most simple illustration of this subject, with the air 
pump, may be made by means of a small vessel of ether ; for 
if this be placed under the receiver, and the air exhausted, 
the fluid will boil, or turn to vapor, during ordinary tempera- 
tures of the atmosphere. 

If a vessel of hot water, instead of the ether, be placed under 
the receiver, and the air withdrawn from it, the water Avill con- 
tinue to boil until its temperature is reduced down to 70 degrees. 
In the absence of an air pump, the same 
principle mpty be strikingly illustrated as fol- 
lows. Adapt a good cork to the glass flask. 
Fig. 1, so as to make it air tight; put a gill or 
two of water into it, and apply the heat of a 
lamp until it boils. After it has boiled for a 
short time, introduce the cork, and at the 
same time take the flask from the fire. It will 
continue to boil for a few minutes after its 
removal. When the ebullition has ceased, 
it will boil again violently on plunging the 
flask into a jar of cold water, as seen in the 

Under what circumstances will water boil at a less temperature than 212 degrees ? 
At what temperature does water boil when the pressure of the atmosphere is removed 1 
How may the pressure of the atmosphere be removed from a vessel of water, without 
thft xi'^ of an air pump ? 

2* 




aB rVAPORATION. 

figTirc. On taking it oiit of ihe water, the eLulIliion vnW 
cease, but will instantly recommence if ag-ain plunged into 
the water, and this may be continued until the flask is nearly 
cold. 

In this experiment, the boiling is continued in consequence 
of the partial vacuum which is occasioned by the condensa- 
tion of the steam with which the flask an as at first filled. If 
the flask be taken from the vessel of cold water, and plunged 
into one of hot water, the boiling will instantly cease, because 
the heat will convert a portion of the water in the flask, which 
had been condensed, into steam, and thus the partial vacuum 
which had been formed will be filled with vapor, the pressure 
of which will prevent further ebullition. 

This })rinciple is beautifully illustrated by the fact, that the 
higher we ascend from the surface of the earth, the lower AviU 
be the temperature at which water boils. The reason is ob- 
rious ; the pressure of the atmosphere diminishes in propor- 
tion to the ascent, and the boiling temperature sinks in pro 
portion as the pressure is removed. 

Upon this principle is constructed the thcnnomctericharomc' 
(tr, which indicates the elevation of any place above the level 
of the sea, by the temperature at which Avatcr boils at that 
elevation. By experiment it has been found that a difference 
in elevation, amounting to nearly 520 feet, makes a difll'r- 
ence of one degree in the boiling point of water. A traveller 
therefore who ascends a high mountain may ascert; :n nearly 
liis elevation, by the iemperaturc at which ne finds his tea- 
kettle to boil. Thus Saussure found that at a certain station 
on Mount Blanc, water boiled when heated to 187 degrees. 
This being 25 degrees less llian its boiling point at the level 
of the sea, allowing 520 feet for every degree, would give an 
elevation of 13,000 feet. This method cannot however be 
very accurate, since the weight of the atmosphere at the samo 
place varies at different times about three inches of the ba- 
rometric guage. [Sec Natural Philosopluj, article Barometer.'^ 

Evaporatioyi. 
During the process of ebullition, there is a rapid formation 
of vapor, attended by more or less commotion in the liquid. 

Why will ihc water In a venspl, fig. 1, be made lo boil by colil ami cease to boil by 
hcAil Wliy ilitcfl watrr Ixiil at a lower teiniH-rulure on a high mountain than on the 
lerel of the seal What inntrumeni is constructed on this principle 1 IIow raay a Ira- 
Tiller who aAcemls a high mountain ascertain nearly his elc\'ation by the twUin^ of a 
iM-koitJc 1 What is ovaporaiion 1 



EVAPORATION. 19 

Evaporation also consists in the formation of vapor without 
heat, but the process is so slow as not to occasion any visible 
commotion in the fluid. Evaporation takes place, even du- 
ring the coldest seasons, while ebullition requires various de- 
grees of heat, or at least the removal of atmospheric pres- 
sure. 

To prove that evaporation takes place at ordinary tempera- 
tures, nothing more is necessary than to expose a quantity of 
water to the open air in a shallow vessel, when the fluid will 
be found gradually to diminish, and finally to disappear en- 
tirely. There is, hoAvever, a great diflerence in the rapidity 
with which difl^erent fluids evaporate, and in general it is found 
that those whose boiling points are lowest, disappear most 
rapidly. Thus, ether, and alcohol, evaporate much more 
rapidly than water. 

The chief circumstances which influence evaporation are, 
extent of surface, and the state of the atmosphere in respect 
to temperature, moisture, and dryness. 

As evaporation takes place only from the surfaces of fluids, 
it is obvious that its rapidity must, under equal circumstances, 
be in proportion to this extent of surface. Thus, a given 
quantity of water will evaporate four times as soon from a 
vessel two feet square, as it will from a vessel of one foot 
square. In respect to temperature, it hardly need to be re- 
marked, that fluids evaporate more rapidly in warm, than in 
cold situations, and that the process is hastened in proportion 
to the degree of heat employed. 

Fluids evaporate much more rapidly in a dry, than in a 
damp atmosphere. Even when the season is cold, if the air 
be dry, this process goes on rapidly, while it is comparatively 
slow, during the warmest season, if the air is already satura- 
ted with moisture. 

As evaporation consists in the formation of vapor, and the 
subsequent removal of successive portions of the evaporating 
fluid, by the air which comes into contact with its surface, it 
is obvious that the process must be more rapid in a current of 
air, than it is in a place where the air is still. And hence we 
find by experience, that evaporation is more rapid in the open 



How is it shown that evaporation takes place without the aid of heat 'J What, relation 
does there seem to be between the boiling point of a fluid and its evaporation 7 What 
Are the chief circumstances which influence evaporation? Is evaporation most rapid 
'm hot or cold weather "i In what does evaporation consist 7 Why is evaporation more 
rapid in *he open air, than in the house ? 



20 LVArORATION. 

air ilian in ilie house, and lliat under equal circumstance's 
is most speedily efTected during a strong wind. 

We liave already explained, that one of the peculiar cir- 
cumstances attending the formation of steam, is the large 
quantity of caloric which it absorbs, and carries away. Now 
It appears by experiment, that the conversion of fluids into 
\aj)or always re(juires large quantities of caloric, which be- 
comes latent in the vapor, however slowly the process is car- 
ried on, and hence under ordinary circumstances, evapora 
lion, by conveying off the heat, has the effect of generating 
cold. To make this fact sensible by experiment, we havt 
only to pour a little ether on the hand, when a strono^ sensa 
tion of cold will be felt during its evaporation. When on 
clothes are wet by a shower of rain, we feel cold for the same 
reason, but the sensation is less strong, because the evapora- 
tion of water is not so rapid as that of ether. 

It has been explained that water boils at a lower tempera- 
ture in proportion as the pressure of the atmosphere is remo- 
ved. For the same reason, evaporation under equal circum- 
stances, is most ra])id when the weight of the atmosphere is 
removed, as under the exhausted receiver of the air pump. 

The cooling effects produced by the evaporation of water 
in the open air are not strikingly apparent, because the pro 
ress is comparatively slow, and therefore the quantity of ca- 
loric carried away from a body in any given time, is but little 
more than it receives from surrounding objects. But whei 
water is jilaced in a vacuum, its evaporation is very rapid, 
and did not the vapor from it fill the vacuum, and thus 
prevent farther evaporation, the heat would be carried away 
so rapidly as soon to turn the water to ice. 

'*^' "" This curious 

effect is produ- 
ced by means 
of an mstru- 
nient invented 

'V Dr. Wollaston, and called the Cryop/iorus, or Frost hearer, 
y'l'j. '^ It consists of two i^lass balls as free from air as pos- 
sible, and joined together by a glass tube. One of the balls 



What it said concerning the latent heat of vapor 7 IIow is cold produced by evapora 
Unn7 Doea iho preMurc of ihe aimtfrphoro jJiHuence this process 1 Why docs not tlie 
cva|wmiion of water from the surface of iho earth proiUice intense cold 7 How may 
the cvnponiiion of water be made so rapid as to turn iu*lf into ice? What is Ui< 
nsirumcnt. Fig. 2, caJlod? 



EVAPORATION. 



21 




contains a portion of distilled water, while the other parts of 
the instrument, which appear empty, are full of aqueous va- 
por, which prevents the farther evaporation of the water by 
the pressure the vapor exerts on it. But when the empty 
ball is plunged into a freezing mixture, all the vapor within 
it is condensed ; and then the evaporation becomes so rapid 
from the water in the other ball, as to freeze it in a few mi- 
nutes. To make this experiment succeed, the tube should be 
a yard long, the balls holding about a quart each. The same 
effect on water will be produced by the evaporation of ether 
under the exhausted receiver of an air pump. 

This experiment may be conveniently made by placing a 
little water in a glass cup, and covering it with ether, after 
Fig. 3. which suspend the cup Avithin the receiver of 
the air pump, as shoAvn at Fig. 3. On exhaust- 
ing the receiver, the ether will boil, in conse- 
quence of its rapid evaporation, and in a few 
minutes the water will be frozen. 

Evaporation takes place constantly, from the 
surfaces of our bodies, and it is owing to this 
circumstance that men are enabled to undergo 
exercise during the heat of summer. 

In general, the more violent the exercise, the 
greater is the quantity of perspiration arising 
from the surface, and consequently the greater 
the quantity of heat carried away. In this 
manner nature regulates the heat of the system, 
and during health sustains the equilibrium of animal tempe- 
rature. Whenever this exhalation from the skin is suppressed, 
which only results from disease, the temperature of the sys- 
tem rises, and fever succeeds. In some cases of this kind, 
the heat of the human body exceeds that of the standard oj 
health by seven or eight degrees. 

The natural temperature of the human body in health, is 
about 98 degrees, and whenever the heat of summer is equa^ 
to that of the body, it becomes exceedingly oppressive. Th 
least exertion then brings on copious perspiration, which, m 
deed, prevents the immediate consequence of a higher am 




How may water be frozen by the evaporation of ether 1 From what provision of na 
ture are we enabled to use violent exercise in warm weather 7 How does perspiratio 
relieve us from thfj efl'ects of excessive heat 1 What is the effect of suppressed perspira 
lioR on the temperature of our system'? 



22 coxDrcTORs of caloric. 

mal temperatuTc, but whicli is generally succeeded by lan- 
g-uor and debility. 

It is a wonderful fact, that the living animal has the power 
of resisting both heat and cold, and of maintaining its own 
temperature, whatever may be the temperature of the air or 
water in which it is immersed. Sir Joseph Banks, and Sir 
Charles Blagden, found by experiment that they could en- 
dure for a short time the heat of a room, the temperature of 
which was 20 1 degrees, that is, 52 degrees hotter than boil- 
ing water. These gentlemen found that their hands, could 
not bf^ar the heat of their watch-chains, or metallic buttons, 
but that their chests felt cold, and that the temperature of 
their bodies was not elevated above 98 degrees. In this 
room, eggs placed in a tin frame, were roasted in twenty 
minutes, and beef-steak was well cooked in about the same 
time. 

Conductors of Caloric 

Some bodies have the power of conducting caloric much 
more rapidly than others. Thus one can hardly hold a brass 
pin for a moment, in the flame of a lamp, without burning his 
fingers, while a piece of glass of the same size, ma}^ have 
one of its ends melted with heat, without warming the 
other. 

Bodies whicli are most dense are generally the best con- 
ductors. Thus the metals conduct better than stones; stones 
better than earth ; earth better than wood ; and wood better 
than charcoal, cloth, or paper. But in particular cases there 
is no relation between the density of the body, and its power 
to conduct caloric. Thus platina is the most dense of the 
metals, and still it is one of the worst conductors among them ; 
and glass is a worse conductor, than many substances of less 
than half its density. 

The conducting powers of different substances, are ascer- 
tained by making rods of the same length and size, of each 
substance; one end of which being coated with wax, the 
other end is placed in a vessel of hot water, and the state of 
the wax on each, at the end of a given time, will show its 
comparative conducting power. 



What i» sQiil of ihe power of animals to rcsisn heal as well as coUl 7 What 5trikln|f 
UluBtrat ion is piven of the ix)wcr of men to resist heat 7 What boilies are pcnerall> tha 
ban conductors of heat 7 Are tlie most dense Uxiies always the bc«t conductors ol heat 
How arc tiie conducting i^owcrs uf difl'crcnt bodies ascertained] 



CONDUCTORS OF CALORIC. 23 

Solid substances, such as the metals, conduct caloric m all 
lirections, whether upwards, downwards, or sideways. Avith 
.learly equal facility. 

Of all solids, those which are most porous, conduct heat 
with the least facility. It is on this account that flannel is 
warmer in the winter, than silk or linen. It does not so 
readily conduct away the animal heat. It is owing to the 
air, which loose spongy substances involve, that they resist 
the passage of heat better than those of a closer texture. — 
Thus eider down, and fur, make the warmest clothing, be- 
cause they contain the most air among their parts, and for the 
same reason cotton batting is much w^armer than the same 
weight of cotton cloth. 

The imperfect conducting powder of snow, also arises from 
this cause. When newly fallen, a great proportion of its bulk 
consists of the- air which it contains, as may be readily proved 
by the comparatively small quantity of water it makes when 
melted. Such a provision was designed for the benefit of 
man, in preventing the destruction of various products of the 
earth during the cold of winter. Farmers, in cold climates, 
always lament the nakedness of the earth during the wdnter, 
because many of their crops are in consequence injured by 
its severity. So great is the protecting effect of snow, that 
in Siberia, it is said, when the temperature of the air has been 
70 degrees below the freezing point, that of the earth under 
the snow has seldom been colder than 32 degrees. 

Our ordinary sensations every day convince us of the dif- 
ferent powers of various substances to conduct heat. In the 
winter, the different articles in a cold room convey very dif- 
ferent sensations to the hand. A pair of tongs w^ill conduct 
away so much heat from the hand as to give a sensation of 
pain, while a piece of fur, or flannel, scarcely feels cold, and 
yet both are of the same temperature, when tested by the 
thermometer. 

Liquids communicate heat vv^ith considerable rapidity, 
though they conduct it so imperfectly that Count Rumford, 



What kind of solids are the worst conductors of caloric 7 Why do loose spongy bodies 
conduct heat more slowly than others'? Why is cotton batting warmer than the same 
weight of cotton cloth 1 In what manner does snow protect the earth from the cold of 
winter 1 What is said to have been the difference between the temperature of the air, 
and the earth covered with snow, in Siberia? Why does a pair of tongs feel cold, when 
a piece of flannel or fur. at the saiiie temperatiu'e gives no sensation 1 How do liquid* 
eonvey caloric. 



21 CONDtCTORS OF CALORIC. 

after many experiments, concluded that they were absolutely 
non-conduclors. 

Liquids convey heat chiefly by a change of place among 
their particles. When a vessel of water is placed over the 
fire, that portion of the fluid nearest the heatliaving imbibed 
a portion of caloric, becomes lighter than before, and rises 
upward, communicating a part of its heat to the portions 
above. At the same lime, that which is above sinks to the 
bottom of the vessel, and having obtained its portion of calo- 
ric, again rises, giving out a share to the surrounding fluid, 
like the former. In tliis manner does the water in the differ- 
ent parts of the vessel exchange places until the whole gains 
the temperature of 212 degrees. 

But though fluids convey heat chiefly by exchanging the 
places of their particles, yet they are not wholly without the 
power of conducting it in any direction. 

Count Kumford, we have already stated, decided from his 
experiments that liquids were perfect non-conductors of heat; 
but Dr. Murray, and since him, other experimenters, have es- 
tablished the contrary doctrine. Dr. Murray's apparatus 
consisted of a vessel of ice, at the bottom of which was pla- 
ced a delicate thermometer. The vessel was then partly filled 
with oil, at the temperature of 32 degrees, so as to cover the 
bulb of the thermometer; and nearly touching the oil, was 
suspended an iron cup, into which was poured a quantity ot 
boiling water. In seven and a half minutes the heat from the 
water had raised the thermometer from 32 degrees to 37^ 
degrees, when it became stationary, and then gradually be- 
gan to fall. 

Dr. Hope placed water in a vessel of eleven inches in dia 
meter, and so contrived his apj^aratus, that a stream of cold 
water should circulate around this vessel, to prevent its con- 
ducting power from aflecting the result. He then applied 
heat to the upper surface of the water in the vessel, and found 
by the indications of a thermometer placed in it, that the fluid 
conducted the caloric downwards. 

By such nice experiments only, has it been ascertained, 
that fluids conduct heat downwards; while under all ordi- 
nary circumstiuices, they may be consideretl perfect non- 
conductors. 



Are flukla wholly wiihoiit Uie power of coniluriing caloric ? Ry uhai mcihod Uiil 
X>r. Murray detcrmiiic that fluiils were conduclora of caloric! In whai maTUeriWil 
Dr. Hope a«c«ruin iho a^io face 



EXPANSION BY HEAT. 



25 



l_r 



O 



Expansive Poiver of Heat. 
One of the most remarkable properties of heat arises from 
(he mutual repulsion of its particles, so that when it enters 
into other substances, it overcomes the cohesive attraction of 
their parts, making them less dense than before, and thus en- 
larging their dimensions. In general terms, therefore, heat 
expands ail bodies. The ratio of this expansion, however, 
differs greatly in different substances. Thus, with the same 
increments of heat, fluids expand more than solids, and aeri 
form bodies more than fluids. There is also a considerable 
difierence in the expansibility of different solids and different 
liquids ; but the aeriform fluids, as air and the gases, all ex- 
pand equally, with the same increase of temperature. 

The expansion of a solid is readily proved, by adapting a 
piece of metal, when cold, to an orifice, or notch, and then 
heating it, when it will be found too large for its former place. 
;, The cylindrical piece of brass, attached 

to the handle a, fig. 4, is exactly fitted 
to the notch in the plate b, and also to 
the aperture through the plate, so that it 
will enter the notch, and pass through 
the aperture, when cold ; but when heat- 
ed, even below redness, it will neither 
enter the notch, nor pass through the 
aperture. This proves that heat enlar- 
ges, or expands the dimensions of solids 
in every direction. 

The relative degrees of expansion 
which different solids undergo, at low de- 
grees of heat, are shown by an mstru- 
ment called the pyrometer, one form of Avhich is seen at Fig. 5. 

A rod of any 
metal, a,is laid 
on the rests, 
and one end 
made to touch 
the immovea- 
ble screw, b, 
while the oth- 
er end touch- 
es the index 
The rod 



Bg, 4. 



/a? 








flow docs heat operate to enlarge the dimeiiMoas of bodies 1 

3 



2G EXPANPTON EY HEAT. 

IS thon heated by the spirrt lamps d, and its comparative ex- 
pansion is shown by the multiplied •motion of the index e 
along the graduated scale. 

In comparing different substances by means of this instru- 
ment, it will be necessary that all the rods should be of the 
same size and length, and that the heat of the lamps should 
be applied the same length of time. 

From experiments made with this instrument, it appears, 
that in most instances, there is a relation between the expan 
sion of the metals, and their fusibility, and in general, that 
those which are most easily fusible, expand most with equal 
increments of heat. Thus lead, tin, and zinc, expand much 
more by the same degrees of heat, than copper, silver, and 
iron, and the former are much more easily fusible than the 
latter. 

The expansion of the metals by licat, is often turned to ad- 
vantage by certain mechanics and artizans in their business. 
In constructing large cisterns for brewers, or other manufac- 
turers, the hoops are made too small for the circumference 
uf the vessel. They are then heated, and in this state driven 
on the vessel, and as they contract in cooling, the vessel is 
tluis bound together more firmly than could be done by any 
other means. Carriage-makers, by heating the iron band, or 
tire, which surrounds the wheels of carriages, and putting it 
in its place while hot, bind these parts together, with the 
greatest possible firmness. 

The great force with which metals contract on cooling, 
was strikingly illustrated some years since in Paris. The 
two sides of a large building in that city, having been pressed 
out by the weight of its contents and the roof, M. Molard pro- 
posed to remedy the evil, by making several holes in the two 
walls, opposite to each other, through which, strong iron bars 
should be introduced, so as to cross the inside of the build- 
:ng, from one wall to the other. On the projecting ends of 
llie bars, on the outside of the building, were screwed strong 
))lates of iron. Tlie bars were tlien heated, bv which their 



What bodice expand leaat, and wluu raoal, by heat 7 WTial is said of the equal 9X- 
p.\asion of air aiid tlie ga«»c« by hcail How is Uie expaiv'ion of a piece of metai 
»li«iwn by flg. 4 7 How ore relative dej;reca of expmsion which solitla undergo as- 
C'Tiincd 7 Explain fig. 5 What n-laiion i.s there between the expansion of nictali 
and thrir fusibilities 7 In what mcrhanical arts is tlie expansion of the ractals, by heat^ 
(u;fietl to advantage 7 In what niaiuuir were iho walls of a building in Paris draWD 
lowardi earh other bv moatis of luai 7 



EXPANSION BY HEAT. 



27 



ends were made to project farther beyond the walls, thus per- 
mitting the plates to be advanced, until they again touched 
the walls, which might be an inch, or more. The bars, then, 
on cooling, contracted, and drew the walls as much nearer 
each other as the bars expanded in heating. There were 
two sets of these bars, so that, while one set was contracting 
and drawing the wall to its place, the other set was heating, 
and prepairing to retain what was thus gained. In this man- 
ner, a force was exerted, which the power of man could 
scarcely have applied by any other means, and by which the 
walls of an immense building were made to resume their 
perpendicular position. 

The expansion of a liquid by heat, may be strikingly shown 
by means of a glass ball, with a long small tube attached to it. 
When the ball, and a part of the neck, are filled with a liquid, 
and heat applied to the ball, the liquid expands, and continues 
to rise up the tube with considerable rapidity, until the liquid 
boils, when it will be thrown out with great force by the 
steam. 

The different expansibilities of different fluids by the same 
increase of heat may be shown by two such vessels as that 
just described. 

On the tube of each, fix a mark at the same 
height and fill one up to the mark with alcohol, and 
the other with water. Then plunge the bulbs of 
both into the same vessel of boiling hot water, thus 
making the heat applied to each, exactly equal. — 
Both the fluids will expand, and rise up the tubes, 
but the alcohol will be found to rise about twice 
as high as the water. 

It has already been remarked, that the ratio of 
expansion in all aeriform fluids, is equal, with 
equal increments of heat. 

If therefore, the ratio of expansion for one gas, 
as for instance, oxygen, be known, then the ratio for all the 
other gases, as well as that for the common air, which we 
breathe, will be indicated. 

From the experiments of several philosophers, it is proved, 
that this rate of expansion is equal to the T^-oth part of the 




In what manner is the expansion of a fluid most strikingly shown 7 How are tlie 
different expansibilities of different fluids shown? Explain Fig. 6. How much more 
♦ixpansible s alcohol than water? What is the ratio of expansion in aeriform bodies ? 



S8 RADIATION OF HEAT. 

volume which the gas occupied, for every degree of FaJir^^^ 
heit's scale, at 32^ and upwards. This calculali(jn is made 
from the experiments of Gay Lussac, who found that 100 
parts, or volumes of air, at 32^, expanded to 137.5 parts, 
when heated to 212°. The increase of bulk for 180 degrees, 
that is, from tlie freezing to the boiling point, is therefore 
37;}-, which, by calculation, will be found nearly i^oth part 
for each degree. 

The expansion of air by heat may readily be shown by 
blowing up a bladder, and securinf^: the moulh by a string, so 
that none can escape, and then holding it towards the fire. 
As the air becomes rarefied by the heat, the bladder will be- 
come more and more tense, until it bursts Avith an explosive 
report. ^ 

A more elegant experiment is, to take a 
glass tube, terminated by a bulb, and put in 
. . so much water as to about half fill the tube, 

u \\ and then, having immersed it in a vessel of 

' ^^ water, as represented in Fig. 7, apply the 

heat of a lamp to the bulb. As the heat 
rarefies the air in the bulb, the water will 
be forced down the tube, but will slowly 
rise again to its former place, by the pres- 
sure of the atmosphere on the fluid, when 
tlu» heat is removed, and the air in the ball 
allowed to contract. 




Radiation of Heat. 
When we approach a heated body we become sensible that 
it emits caloric without touching it, and if a thermometer be 
cacried near, this will indicate an increase of temperature. — 
The caloric thus flowing from a heated body, is called radiant 
caloric, because it radiatcs^oT is thrown ofTin all directions, 
like the rays of light from a radiant point. If the hand be held 
under the heated body, a sensation of warmth will still be 
perceived, which proves that this effect is produced without 
the intervention of a stream of heated air, which is felt only 
above the hot body, and never below it. Neither ?s this 
cfTect produced by the gradual conduction of the caloric 
by the air, for the heat from a hot ball may be felt in the 

What to Ihe difTcrcncc in tic bulk of lOi) jvirts of air al the freezing and boiling poinw 
of watarl ^^'hat simple expcrimenis show Uic cxiKui5ion o{ air by heati — Explain Fig 
7. Whai ifl meant by nulianl heal i How is it proved that railianl heal 10 not conducK*! 



RADIATION OF HEAT. 29 

open air, at a distance from it and in the direction contrary to 
that of the wind. It is found also, that caloric radiates equal- 
ly well through all the gases, and better through a vacuum 
than any medium; and hence we may infer that no medium 
at all is necessary for the passage of radiant caloric. 

When radiant caloric falls upon a solid or liquid, its rays 
are either reflected from it, an^thus receive a new direction, 
or they lose their radiant form entirely by absorption into the 
body. Thus, a substance highly polished will throw the heat 
back, towards the radiating body, and remain cold itself; while 
another substance, with a rough surface, will become warm at 
the same distance, because it absorbs, but does not reflect the 
heat. Radiant heat, and light, follow exactly the same laws 
in their passage to and from polished surfaces, the angles of 
incidence and reflection being equal. 

Fig. 8. a Thus the ray a, c, Fig. 8, is the ray of inci- 
dence, and c, d, is the ray of reflection. The 
angles which a c make with the perpendicular 
line e c, and the plane of the mirror, are exact- 
ly equal to those made by c, d, with the same 
=^perpendicular, and plane surface. [See Optics 
in Nat. Philosophy.) Hence with a concave 
mirror, the rays of heat, like those of light, 
may be concentrated, or collected to a focus, 
and by m^ai.3 of two such mirrors, very inter- 
esting experiments may be made, illustrating the 
laws of radiant heat, in several respects. 

Provide a pair of concave metallic mirrors, about ten or 
twelve inches in diameter, and two in concavity. They may 
be made of common tinned iron, or of brass, which is better, 
but much more expensive. 

Fig, 9. These mir- 

rors may be 
supported by 
stands made 
of wood on 
which they 
slide up and 
do-^Ti, and 
are fixed by 
thumbscrews 
^ y^ as represent- 
Cs=^ ed in Fig. 9 





TIow is i: ehown that no medium a. all is necessary to coavey radiant caloric V 

3* 



to RADIATION OF HEAT. 

Place the mirrors at the same height, on a bench or table 
exactly facing each other, and from ten to twenty feet apart 
as they are less or more perfect, and place a screen of paper 
or other substance between them. Then in the focus of one 
mirror place a cannon ball, heated a little below redness, and 
in the other focus place a thermometer. When every thing 
is thus prepared, remove ih^ screen, and the thermometei 
will ini<tanlly bei:in to rise, and will finally indicate a degree 
of temperature depending on the size and perfection of the 
mirrors, their distance apart, and the heat of the ball. The 
focus of a twelve inch mirror of the orcfinary shape, is about 
four and a half inches distant from the centre of concavity. 

By placing the mirrors near each other, and using a red 
hot ball, a much more striking experiment may be made, for 
on removing the screen, powder will flash in the focus as if by 
magic, since the eye cannot detect the cause on which its 
inflammation depends. 

The dotted lines in the drawing. Fig. 9, show the course 
of the ray* of heat from the hot ball to the thermometer. 
The ball being placed in the focus of the mirror, the caloric 
radiates to all parts of its surface, and being reflected under 
the same angles at which it falls, the rays are thrown into pa- 
rallel lines, and thus become incident rays to the second mir- 
ror. By the same law of incident and reflection, the se- 
cond mirror conveys the rays to a focus at the same distance 
before it, that the hot ball is placed before the first mirror, 
because their focal distances are just equal. The heat of 
the ball is therefore concentrated on the bulb of the ther- 
mometer, which is placed in the focus of this mirror. If a 
burning lamp be placed in the focus of the first mirror, and 
a piece of paper, or the hand, in the focus of the second, 
there will be seen a bright luminous spot on the paper or 
hand, showing that light follows the same laws of reflection 
that heat does. 

There is however a remarkable difTerence belween the sub- 
stances of which mirrors are commonly made, with respect 
to their powers of reflecting heat and light. A concave glass 
mirror, covered in the usual manner with amalgam, when 
placed before a red hot cannon ball, will reflect the light. 



Doca heal radiate through eoliil UmIIiy. ? Explain Fig. 8, and show which is Oxa 
my of incidence and which tluil of rrncciion. Explain Fi?. 9 ; show llic dirccti(ji of 
Uic ray« of heal from Uic heated lull U) liic mirrors, and from Die iiiirvor lo the tlicr- 
inom<t«-r. How is it shown by the mirror that heal and liglit follow iha same lawi 
df roAcavoQ 1 



RADIATION OF HEAT. 



81 



out not tlie heat, the mirror itself absorbing the radiant ca- 
oric, and soon growing warm. But a well polished metallic 
mirror reflects both the heat and light, and although held so 
near an ignited body, as were it combustible, to be inflamed, 
it still remains cold. For the same reason, andirons, which 
are kept highly polished, will remain cold though near a 
winter's fire. Any one who has undertaken to boil water in a 
silver cup before the fire, will be convinced of the power of a 
bright metallic surface to resist the penetration of caloric. 

The nature or colours of the surfaces of bodies have also 
an important influence over their power of radiating caloric. 
When other circumstances are equal, the rate at which 
bodies cool appears to be in an inverse ratio to the polish, 
or brightness of their surfaces. Thus, the surfaces of bodies 
are found to radiate heat more rapidly when they are rough 
than when smooth, and most rapidly when their surfaces are 
both rough and dark coloured. 

Mr. Leslie covered one side of a cubical tin vessel with 
lamp black, another side with writing paper, a third with 
glass, and left the fourth uncovered. 

The vessel was then filled with hot water, and placed 
before a concave mirror, in the focus of which was placed 

an air thermometer, as repre- 
sented by Fig. 10. On turning 
the black side towards the re- 
flector, the fluid in the ther- 
mometer indicated a rise of 
temperature equal to 100°; 
the papered side being turned 
towards the reflector, the 
thermometer sunk to 98° ; 
the glass side indicated 90° ; 
and the metallic side only 
12°. The radiating power 
of these surfaces, therefore, 
are respectively to each other as the numbers 100, 98, 90, 
and 12. 




What is the difference between a mirror of glass and one of metal, in their powers to 
reflect heat and light 7 Why do polished andirons remain cold when near the firei 
Why is it difficult to boil water in a bright metallic vessel 7 What effect does the nature, 
or color of a surface, have on its radiating power 7 Describe Fig. 10, and explain how 
C» different surfaces affect the thermometer 



32 SPECIFIC CALORIC. 

Various practical uses may be made of this principle m 
the common concerns of life. 

A close stove, intended to warm a room by radiatmsf Us 
heat to the objects surrounding it, should be dark coloured, 
with a rough surface; while one intended to warm with hot 
air passing through it, should have a bright metallic surface 
A dark, rough stove })ipe, passing through a room, miglit ren- 
der it comfortably wiirm; while a polished tin pipe, of the 
same length and dimensions, would liardly change its tem- 
perature perceptibly. For the same reason, a highly polish- 
ed metallic cotlee pot will keep its contents hot, while the 
contents of one made of dark earthen ware would become 
nearly cold. 



Specific Caloric. 

Equal weiglus of the same substance, at the same tempe- 
rature, contain equal quantities of caloric ; but equal weights 
of different substances at the same temperature, contain un- 
equal quantities of caloric. The quantity peculiar to each 
b<3dy, or substance, is called specific cahric. When one 
body of the same weight is found to contain more caloric 
than another, that containing the most, is said to possess the 
greatest capacity for caloric. 

When equal quantities of the same fluid at different tem- 
peratures are mingled together, the resulting temperature is 
a medium between these temperatures. Thus, if a quart oi 
water at 100'\ be mixed with another quart of water at 40^, 
the temperature of the mixture will be 70^. The same re- 
sult will occur when any other liquid is mixed in equal propor- 
tions, but at different temperatures, as oil, alcohol, or mer- 
cury. Hut when equal quantities of different fluids are min- 
gled tOLTcther, at different temperatures, the resulting tern- 
])erature is not a medium, but is either above or below it. 

We should expect without experiment, that quicksilver 
would possess a greater capacity for caloric than the same 
bulk of water, and therefore that when equal quantities of 
these two fluids at different temperatures are mixed, the 



Wbai pnicilad use* may be mad« on the principles established by Mr. Leslie's eipc 
rimrnil Why tloea a bright coflcc pot ket'p its content-s warm longcrihan one that is 
tarni«hed 7 What i« meant by specific caloric 1 What is monnt by caiiaciiy for caloric "» 
HupjH*:*; c<]ual quaniiiie-s of ilie same fluid at dilTcrciu lcini>araiurc8 arc mixed, wha 
^111 bo Uie roatdiMij '.emperaiure 1 



SPECIFIC CALORIC. 35 

resulting temperature would be above the arithmetical mean. 
But in this we are disappointed ; for if we mix a quart of 
water at 40^ with a quart of quicksilver at 100°, the tempe- 
rature of the mixture will not be 70°, as in the experiment 
with the water alone, but only G0°. This proves that a 
quart of quicksilver, although it weighs about fourteen times 
as much as a quart of water, still contains less caloric, and 
therefore that water has a greater capacity for caloric than 
quicksilver. For, in the first experiment, a quart of water 
at 100° raised the temperature of another quart at 40° to 
70°; but here a quart of quicksilver at 100° raises the heat 
of the same bulk of water to only 60°. The quicksilver, then, 
loses 40°, which nevertheless raises the temperature of the 
water only 20°. 

The relative capacities of water and quicksilver for heat, 
may be shown by mixing equal weights of the two fluids at 
different temperatures, and then ascertaining how much the 
resulting temperature differs from the arithmetical mean. 

Mix a pound of water at 100° with the same weight of mer- 
cury at 40°, and the heat of the mixture will be 98°; that is, 
28° above the arithmetical mean, because when equal 
weights of water were mixed at these temperatures, the re- 
sulting temperature was only 70° ; but here it is 98. The 
water, then, has lost only 2°, while the same w^eight of mer- 
cury has gained 58°, for the temperature of the mercury be- 
fore the mixture was only 40°, while that of the water wac 
100°. The capacity of water for heat, is therefore to the 
capacity of mercury for the same, in the proportion of 58 to 
2, or as 29 to 1. 

It appears from a great variety of experiments made by 
different philosophers on this curious subject, that whatever 
may be the cause of the different capacities of bodies for 
heat, the effect is greatly influenced by the state of density in 
which bodies exist, and that in general their capacities in- 
crease, in a ratio to the decrease of their specific gravities. 
In the above experiment, the capacity of water is to mercury 
as 29 to 1, while their specific gravities are as 1 to 14. 

Various methods have been employed by philosophers to 
ascertain the capacities of the several gases for heat. 



^^^len fluids of different kinds are mixed under the same circumstances, will the result- 
ing temperature be a medium 1 Which fluid has the greatest capacity for caloric, water 
or quicksilver 7 How is this shown ? If a pound of mercury at lO** be mixed with a 
pound of wdter at 100^, what will be the resulting temperature? 



84 8PKCIFIC CALORIC. 

To determine and compare the relative capacities of these 
bodies in this respect, Gay Lussac contrived an apparatus, by 
means of which, a hot current of one n-as met a cold current 
of another gas, in the centre of a small reservoir, containing 
a thermometer. A thermometer was also placed in the cur- 
rent of each gas before they met. Thus by knowing their 
temperatures before their mixture, and afterwards, it was easy 
to infer tlieir respective capacities for caloric. 

Bernard, in order to determine the specific caloric of elas- 
tic fluids, caused them to pass through a pipe inclosed in a 
hirger pipe, the laltiT being constantly fillecl with steam. In 
this manner he was enabled to know precisely the temperature 
of the gas under exj)eriment, and also to raise the tempera- 
ture of each to the same degree. Having thus determined 
its temperature, the gas was then made to pass into a spiral 
tube immersed in cold water, and the specific caloric of each 
gas was inferred by the quantity of heat it imparted to the 
water. By these and similar experiments, it has been ascer- 
tained that the aeriform fluids dilfer greatly in the quantities 
of their specific caloric, — thus, the capacity of hydrogen for 
caloric is more than 12 times greater than the capacity of an 
equal bulk of atmospheric air, though the air weighs about 13 
times as much as the hydrogen. It is also ascertained that 
out of nine gases on which experiments were made, none ex- 
cept hydrogen has a capacity for heat equal to that of water, 
but that they all have i^reater capacities than any of the me- 
tals. Hydrogen, the liglitest of all bodies, has the greatest 
capacity for heat, while the metals, the most ponderous of all 
hollies, have the least. 

The same substance by having its bulk enlarged, and con- 
sequently its density decreased, acquires an increased capa- 
city for caloric. I'hus water, when thrown on the bulb of a 
thermometer, sinks the mercury, because, in assuming the 
form of vapour, its capacity for caloric is increased, and it 
consequently absorbs and carries away the heat from the mer- 
cury. Some philosophers have accounted in part, for thfe 
intense cold in the upper regions of the atmosphere, on tho 



What are the proportionate capaciiic« of mcrrur>' and water for heal ? In general, do 
lh« c-apAcitieii of bodies for heat increase, or dccrca-se, with llicir densities 7 By wlial 
method di 1 Ciay LusKac dclorminc ihc ca|wniie8 of ihe ga^ses for caloric? By what ni« 
ihod did Uern&rd determine tnc cojviciiica of the gases for caloric? What gas lias tl . 
greaieM caj^acity for heat ? In general, what claa of bodies luivc ilic greatest, and vhi 
liie \%ui capacity for heal ] 



THERMOMETER. 35 

supposition of the increased capacity of the air for heal as 
the pressure of the incumbent atmosphere is removed. On 
the contrary, we know, that by increasing the density of air, 
its capacity for caloric is diminished, and that under certain 
circumstances sufficient heat may be set free in this manner 
to produce ignition. 

Fig. 11. This effect may be produced by the little instru- 
ment represented by Fig. 11. It consists of a metallic 
tube ten, or twelve inches long, the bore of which is 
less than half an inch in Aimeter. To this is fitted 
a rod and piston, moving air tight, the lower end of 
the piston being excavated to receive a little tinder. 
When the pis-ton is suddenly forced down, nearly to 
the bottom of the tube, the condensation of the air it 
contains, evolves so much heat, as to set fire to the 
tinder in the end of the piston, and in this way a fire 
ma} conveniently be kindled. 

Thermometer, 

The thermometer is an instrument founded on the principle, 
that the expansion of matter is proportional to the augmen- 
tation of temperature, and is designed to measure the varia 
tions of heat and cold. 

The first attempt to measure such variations on this prin- 
ciple was made by Sanctorius, an Italian physician, in the 
seventeenth century. He employed a glass tube blown into a 
ball at one extremity, and open at the other. After expelling 
a small part of the air by heating the ball, the open end was 
plunged into a vessel of colored fluid, and as the air in the 
ball cooled, the fluid ascended up the tube. Any variation of 
temperature by expanding, or contracting the air in the ball, 
would then cause the liquid in the tube to rise or fall. An 
arrangement of this kind is represented at Fig. 7 



If a body has its bulk enlarged, is its capacity for heat increased or diminished there- 
by 1 How has the intense cold of the upper regions been accounted for on this princi^ 
pie 1 How is it proved that the air has less capacity for heat when condensed than 
otherwise? On what principle is the thermometer constructed? Who first corv 
Btructed thermometers ? What fluid was fjrst employed to indicate tlie raxiations of 
temperature ? 



36 

Fig. 



THERMOMETER. 



12. A better construction for an air thermometer is 
represented at Fig 12. It consists of a thin glass bot- 
tle, containing a small quantity of a colored liquid, and 
stopped closely by a cork. Through the cork is passed 
a broken thermometer tube, open at both ends. This 

I tube descends nearly to the bottom of the bottle, and 
dips into the fluid. There is, therefore, a quantity of 
air above the fluid which cannot escape, and when this 
expands by the application of heat, the fluid is forced 
r^ up the tube. Thus the height of the fluid will indicate 
/ \ the expansion of the air, and consequently, the degree 
^^ of heat to which the instrument is exposed. 
There are, liowever, two objections to the employment of 
air for this purpose. Its expansions and contractions are so 
great even by small changes of temperature, that a tube, se^ 
veral feet in length would be required to measure them; and 
as air suffers condensation by pressure, the variation of the 
barometer would affect its height, at the same temperature. 
. For these reasons, the air thermometer, for common pur- 

[)0ses, is both inconvenient and inaccurate, and therefore has 
ong since been laid aside. There is, however, a modifica- 
tion of this instrument, invented by Mr. Leslie, and called 
the differential thermometer, which for certain purposes is a 
very elegant and useful instrument. 

/V/f. 13. A drawing of this instrument is represented by 
Fig. 13, and it is designed, as its name imports, to 
shew the difTerence of temperature between two 
places at short distances from each other. It con- 
sists of a glass tube terminated at each end by a 
bulb, and bent as shown in the figure. The tube 
is partly filled with some colored fluid, as sulphu- 
ric acid, tinged with carmine, or alcohol, colored 
by cochineal, the bulbs and other parts of the tube 
being filled with air. ; 

It will be obvious, from the construction of this 
instrument, that it cannot indicate the temperature 
of the atmosphere, since an equal expansion of 
the air in both bulbs would press equally on the 
fluid in both legs of the tube, and consequently 
it would rise in neither. But if one bulb is ex- 
Describe ihe coivnruciion of an air (licrmomeier. Wliat are tlie objectiona lo air thcr- 
momeicnl How ifl Uie diflcreiKial ilicrmomcter conptructcd, and for what yurpoeoe fi 

t IMWflJ, 




THERMOMETER. 87 

posed to a higher temperature than the other, then the ex- 
pansion of the air in this, will be greater than in the other, 
and consequently the fluid will rise towards the bulb where 
the air is least expanded. 

The use of this thermometer, then, consists in showing the 
difference of temperature to which the two bulbs are exposed, 
as in experiments on the radiation of heat, already described. 
The scale affixed to one of the legs, shows the rise in degrees, 
and is divided into 100 parts. The legs are six inches long, 
and the bulbs an inch or a little more in diameter. The 
stand may be of glass or wood. Some of these instruments 
are so delicate as to be affected by the approach of the hand. 

Air, being inapplicable to the construction of thermometers 
for the purpose of measuring the absolute temperature of 
places or things, for the reasons already noticed, solid bodies 
are equally so from a contrary defect ; their expansion by 
heat being so small as not to be appreciated without the 
adaptation of complicated machinery. A perfect substance 
foi this purpose, would be a fluid, which would expand uni- 
formly wdth equal increments of heat, and which would nei- 
ther freeze nor boil at any temperature to which it might be 
exposed Mercury approaches nearer to these conditions 
than any other substance, and therefore this is the fluid now 
almost universally employed. 

The blowing of the best thermometer tubes requires much 
experience and skill in the workmen, and is performed only 
by particular artists. This is the most difficult part of its 
construction. The mercury is introduced by heating the 
bulb, and thus rarefying the air within it, and then dipping 
the open end of the tube into a vessel of the fluid. As the air 
contracts within by cooling, the pressure of the external at- 
mosphere forces the mercury to enter the tube to supply its 
pJace. When the bulb is nearly filled in this way, the mer- 
cury is boiled, to expel the air. 

Having filled about one third of the tube, the open end is 
sealed hermetically, that is, by melting the glass. This is 
done while the mercury in the bulb is heated nearly to its 
boiling point, so as to exclude all the air. 

Having sealed the end of the tube, the next step in the 

Why will not the differential thermometer indicate the temperature of the atmos- 
phere 1 Why are not solid bodies proper for the construction of thermometers 1 
What would be a perfect substance for the construction of thermometers ? What is 
the most perfect fluid in our possession for thia purpose 1 How are thennometer tubos 
fiUedY 

4 



88 THERMOMETER. 

construction of the thermometer, is its graduation. This is 
done by ascertaining two fixed and invariable points on the 
tube, which arc the same in every thermometer, and then by 
making a scale of equal divisions between these two points 
Tiiese are the freezing and boiling points. 

The freezing point is found by immersing the bulb o 
the thermometer in melting snow or ice, for it has been as 
certained, that the temperature of water flowing from meltini- 
5now or ice, is every where the same, whatever may be thtr 
heat of the atmosphere where the experiment is made. The 
boiling point is slightly afTected by the pressure of the atmos 
phere ; but the thermometer will be sufficiently accurate fo; 
all ordinary purposes, when this point is ascertained by im 
mersing the bulb in pure boiling water, open to the air, and 
on the level of the sea, during pleasant weather. (See Ba 
rometer, in Nat. Philosophy.) 
Fis^. 14. The freezing and boiling points are marked with 
a diamond or hie, on the tube ; and on the scale to 
be afterwards affixed, the freezing point, is marked 
32, and the boiling point, 212. The interval be- 
tween these two points is then accurately divided in- 
to 180 equal parts. This is the division of Fahren- 
heit's scale, the thermometer generally employed 
in this country, and is the only scale referred to in 
this work. 

The commencement of this scale is 32 degrees 
below the freezing point, and is called zero, being 
marked with the cipher 0, to signify the total ab- 
sence of heat. This degree of cold, it is sup 
posed, Fahrenheit obtained by mixing snow and 
common salt, and it was probably the greatest de 
gree of cold known in his time, though at the pre 
sent day certain mixtures produce much greater, 
and at a future period, the progress of science may 
show^ the means of abstracting heat, so as to solidify 
even the air we breathe. 'J'he absolute zero must 
therefore be considered an imaginary point. 

Besides the Zero and the freezing and boiling 
points, marked on Fahrenheit's scale, Fig. 14, 
there are also noted the temperature of the blood, 
and the heat of summer, and sometimes other 
points, as fever heat, (fee. 



How i« ilie freezing point oC the ihermonielcr aaccrtAiiied 7 How is the boiiH»g \>o\vti 
leeenained 1 



COLD 39 

Cold. 

Cold is a negative condition, and depends on the absence, 
or privation of heat. Intense artificial cold may be produced 
by the rapid absorption of heat during the conversion of 
solids into liquids. Dr. Black long since discovered the 
principle, that when bodies pass from a denser to a rarer state, 
neat is absorbed and becomes latent in the body so transform- 
ed, and consequently cold is produced. And also that when 
bodies pass from a rarer to a denser state, their latent heat is 
evolved, anu becomes sensible. 

It is known to almost every one, that dissolving common 
salt in water, particularly if the salt is fine, will render the 
water so cold, even in summer, as to be painful to the hand. 
The salt, as it passes from the solid to the liquid state, absorbs 
caloric from the water, and thus the heat that was before sen- 
sible, becomes latent, and cold is produced. 

On the contrary, when a piece of lead or iron, is beaten 
smartly with a hammer, it becomes hot, because the metal, in 
consequence of the hammering, has its capacity for calorie 
reduced, and thus the heat which Avas before latent, now be- 
comes sensible. For the same reason, when air is compress- 
ed forcibly in a tube, or as it is sometimes called, in a Jire- 
pump, as already explained, the heat, which was before latent, 
becomes sensible, because the condensation lessens its capar 
city for caloric. 

The principle on which all freezing mixtures act, is there- 
fore the change of state, which one or more of the articles 
employed undergo, during the process, and this change con- 
sists in an enlarged capacity for caloric. The degree of cold 
will then depend on the quantity of caloric which passes 
from a free to a latent state, and this again will depend on 
the quantity of substance liquefied, and the rapidity of the 
licuefaction. 



What numbers are marked on the scale at the freezing and boiling points 1 What ia 
the number of degrees between these two points 1 What does zero signify ? How far 
below the freezing point is the zero of Fahrenheit 1 Is the point of the absolute zero 
known 1 What is cold? How may intense artificial cold be produced 1 When bodies 
pass from a denser to a rarer state, is heat or cold produced 1 How is the temperature 
of water generally known to be affected by dissolving common salt in it 1 How is thia 
change of temperature accounted for 1 Why does a piece of iron become hot by ham- 
jnering 7 How do you account for the heat evolved, where air is compressed 1 What is 
the principle on which freezing mixtures act 1 On what circumstance vnll the degree g( 
cold produced by freezing mixtures dejjend 1 



40 COLD. 

The substances most commonly employed for this pnrposc 
are those oriirinally used by Fahrenheit, to ])roduce ilie zero 
of his therniometric scale ; viz. common salt and snow, or 
pounded ice. For this purpose the salt should be fine, and 
the ice, which must always be used in summer, is to be re- 
duced to small particles in a cold mortar. 

Fig. 15. The vessel to contain the substance to be 

f I — p frozen, may be made of tin, and of the shape 

I represented by Fig. 15. It is simply a tall ves- 

I sel, holding a few pints, with a close cover, and 

a rim round the top, for the convenience of 
handling it. For common purposes, this may 
be set into any convenient wooden vessel, (hav- 
ing first introduced the substance to be frozen,) 
and then surrounded by the freezing mixture. 
The only care to be taken in this part of the 
process is, to see that the freezing mixture in 
the outside vessel reaches as high as the con- 
tents of the internal one. With two or three pounds of fine 
common salt, and double this weight of pounded ice, three or 
four pints of iced cream may be made in this way, during the 
warmest days of summer. The process requires two or 
three hours, and while it is going on, the vessel should be set 
in a cellar, or covered with a flannel cloth, as a bad conductor 
of the external heat. 

When the thermometer is at 32°, the cold generated by 
the above process, sinks it down to zero, as above stated. By 
this method, two solids are changed into liquids, and both du- 
ring the change, absorb caloric from the contents of the inner 
vessel. The salt melts the ice in consequence of the avidity 
with which it imbibes moisture, or by reason of its afiinity to 
water, and the wafer in its turn dissolves the salt. 

Other substances having a stronger aflhiity (see affinity) 
for water than common salt, will produce the same effects 
still more powerfully. Thus, muriate of lime (see this article) 
fixe, parts, and ice four parts, will sink the thermometer from 
32*^ to 40^ below zero, that is, in the whole, 72 degrees. At 
this temperature, mercury freezes. A still more eflTective 
mixture is four parts of fused potash, and three parts of snow. 



W)ial are the subsiancea niort commonly used ns freezing mixtures 7 Explain Fig. 
IS, aud show how il is lo be used. How far below 32 dcgrceij will a mixture of ice a*W 
common salt sink the thermometer 1 \Miy docs the salt melt the ice 7 'WTial subeUDOt 
■inks the ihermoiuetei from 32 to 40 degrees below zcr*^l 



60URCES OF CALORIC. 41 

This is said to sink the mercury from 32° to 50° below zero, 
that is, 82 degrees. In these experiments the thermometers 
are filled with alcohol, instead of mercury. 

Freezing mixtures are also made of a solid and a fluid. 
One of the most effectual of this kind is composed of diluted 
sulphuric acid and snow, or pounded ice. This sinks the 
mercury from 32° to 23" below zero. 

Though ice or snow is commonly employed for this pur- 
pose, still powerful frigioric effects may be produced without 
either, the absorption of caloric being caused by the rapid 
solution of a salt in a fluid. One of the most common and 
cheap among these is a mixture of sulphate of soda or Glau- 
ber's salt, and diluted sulphuric acid. This sinks the mer- 
cury from 50° to 3° above the freezing point, that is 47°. 

In describing experiments of this kind, it should always be 
noted from what point the thermometer begins to descend, 
otherwise no judgment of the power of the freezing mixture 
can be formed. If, for instance, a mixture would cause the 
depression of the thermometer from, and below any given 
point, then by repeating the process continually, we should 
be able to find the absolute zero. Thus, by means of muriate 
of lime and snow, the thermometer is made to sink 82°, that 
is, from 32° above, to 50° below zero. Now if the same 
cause would again produce the same effect, by its re-appli- 
cation, the thermometer would sink to 132° below zero, a 
degree of cold never yet produced by any means. But an 
unlimited degree of cold can never be produced by the art of 
man ; for it is found on experiment, that when the tempera- 
ture produced by the freezing mixture is greatly below that 
of the air, the caloric is so rapidly communicated, as to pre- 
vent any effect by repeating the process. Mr. Walker, who 
made a great number of experiments on this subject, was 
never able to produce a greater degree of cold than that of 
100° below the zero of Fahrenheit. 

Sources of Caloric. 
The sources of caloric may be reduced to six, viz. The 



In these experiments, why is alcohol used to fill the thermometer, instead of mercury 1 
What is said of sulphuric acid and snow, as a freezing mixture 1 What substances form 
a freezing mixture without the use of ice or snow 7 In making experiments with freezing 
mixtures, why is it necessary to state the degree from which the thermometer begins to 
Ml 1 What is tlie reason that an unlimited degree of cold cannot be produced by ail I 
What is the greatest degree of cold ever produced 7 What are the sources of caloric ? 

4* 



42 BOTJRCES or CALORIC. 

Sun, Combustion, Electricity, the bodies of living warni 
blooded animals, Chemical action, and Mechanical action. 

The Su7i constantly radiates caloric to the earth, and is 
the great fountain oi heat to us and to the whole solai 
s^^stem. 

Combustion. This supplies the heat employed in the arts, 
and for culinary purposes. In this process the caloric is ex- 
tricated from the oxygen of the atmosphere, as it unites with 
the burning body and supports its combustion. The light is 
supposed to be furnished by the burning body. 

Electricity. Whenever two bodies in opposite electrical 
states are made to approach each other, so as to produce a 
discharge through the air, or along a nonconductor, there 
appears a flash of light attended by heat. By the action oi 
Galvanism, which is a modification of electricity, the most 
intense heat hitherto known has been produced. 

When the electric fluid passes through a piece of metal, or 
Other conductor, of sufficient size, no phenomena are produ- 
ced ; but in its passage through a nonconductor, or through a 
conductor which is too small to admit of a free passage, heat 
is produced. {Sec Electricity, in Nat. Philosophy.) 

Vital action. The bodies of air breathing animals are a 
continual source of heat. The numerous theories which 
have been invented to account for the cause of animal heat 
cannot here be investigated. That it however depends on 
the oxygen of the atmosphere which we breathe, seems to be 
proved by the fact, that animal warmth cannot for any length 
of time be sustained without it. 

Chemical action. Chemical action without combustion is 
capable of producing considerable degrees of heat. If water 
be thrown on unslacked quicklime, in small quantities nt a 
time, its heat will be gradually augmented to nearly 1000 
deg., or so as to ignite wood. The heat in this experiment 
is accounted for, on the law already explained, that when 
bodies pass from a rarer to a denser state, caloric is evolved. 
The slacking lime absorbs the water and retains it as a part 
of its substance, and thus a fluid is converted into a solid, 
w^ith the evolution of much caloric. 



"NVliat is the great fountain of hrat t How is heat extricated by combustion 1 "WTicn 
doe« cleciriciiy pHnluce heal 1 Wliat u? the cause of clecirical heat, according to Sir 11 
Dary 1 What is said of vital acii«i, ai? a cause of heal 1 What is said of chemical ac 
lion as the caiLse of heal 1 How is ilic heat proiluccd by throwing water on (juickliino, 
mccount«d for 1 



SOURCES OF CALO/IIC. 43 

If three parts of strong sulphuric acid and one of water be 
suddenly mixed together, a degree of heat considerably, 
above that of boiling water will be produced. In this case 
the heat is also accounted for on the principle of condensa- 
tion, for if the two fluids be measured before and after mix- 
ture, it will be found that their union has occasioned a loss 
of bulk, and probably also a loss of capacity for caloric. 

The inflammation of Spirit of Turpentine by nitric acid 
is a case of intense chemical action, in which 1000 de- 
grees of heat are evolved. About an ounce of the turpentine 
with the same weight of nitric, mixed with a little sulphuric 
acid, are the proportions. The acid should be poured on 
the turpentine from a vessel tied to a line several feet long, 
as the explosion sometimes throws the burning matter to a 
considerable distance. 

Mechanical action. This mcludes percussion, friction^ and 
condensation. 

Caloric is evolved by the percussion of hard bodies against 
each other. This is owing to the condensation of the body 
struck, in consequence of which its latent heat becomes sen- 
sible. 

If a piece of soft iron be struck smartly several times with 
a hammer, on an anvil, it becomes hot, and even red hot, if 
the experiment be well conducted. 

When a piece of steel and a flint are struck together, the 
condensation produces so much heat as to set Are to the 
small particles of steel which at the same time are struck off 
by the blow. 

Friction. Caloric is evolved, or produced by friction. 
The friction of machinery when the motion is rapid, frequent- 
ly causes so much heat as to set the wood on fire. The in- 
habitants of various nations obtain fire by rubbing pieces of 
dry wood together. The friction of carriage wheels some- 
times sets them on fire. 

Th^ principle on which caloric is produced by friction has 
not been demonstrated. It cannot be referred to condensa- 
tion, since the rubbing of two soft bodies together, such as 



When sulphuric acid and water are mixed, what is the cause of the heat produced "? 
How may spirits of turpentine be inflamed by chemical action 1 What does mechan. 
ical action as a source of heat include 1 How is the evolution of heat by percussion 
accounted for 7 When a piece of steeV is struck by a flint, how is the fire produced 1 
How is the heat produced by friction accounted for'J How does condensation pro- 
duce heat 1 



44 LIGHT. 

(he hand against the coat sleeve, or the two liands against 
each other, causes heat. 

Count Kumford, who made a laborious and varied course 
of experiments on this subject, was led to the conclusion that 
the heat produced by friction could not be connected with 
the decomposition of oxygen gas, nor with the increase ol 
density, nor could it be caused by any change in the specific 
caloric of bodies. Others liave also made experiments with 
a view to determine this question, but as yet no one has pre 
tended to give any satisfactory explanation of its cause. 

The Cuiidcnsatioyi of an elastic fluid by sudden pressure 
causes heat, as has already been explained, and illustrated 
by Fig. 11. The heat evolved in tiiis «ase arises simply 
from the diminished capacity of the air for caloric, in conse- 
quence of its increased density. 

Light. 
The next imponderable agent which falls under our notice, 
is light. The investigation of the properties of light, — its 
laws of reflection and refraction, and its effects on the sense 
of vision, and subjects belonging to the science of Optics. 
(See Optics in Nat. Philosophy.) Some of the efllects of 
light are however properly considered here, since they pro- 
duce chemical phenomena. 

Light may be decomposed by means of a prism, into seven 
primary colours. The succession of these colors, beginning 
with the uppermost, is violet, indigo, blue, green, yellow, or- 
ange, red. 

The decomposition of light, only requires that a ray should 
be admitted tlirough a small aperture into a room, and made 
to pass through a triangular prism, as represented by Fig. 
16. 

The direction of the 
ray towards the poini 
c w^ill be changed bv 
ithe refractive power of 
the prism, and at the 
same time it will be de- 
composed into the col- 



Fig. 16. 




To what 8cicncc (!oc3 the invesiisation of the prnjvrliea of lip:ht, with its eflrect§"Dr 
the Bcnsc of vision, l)clon? 1 Why do some of tlje offecia of liehi properly bolonj^ lo ih# 
rnvc-nigaiionn of chemistry 7 Imo how many primary colors may light be divided 
What is the succeasion of ihcjjc colors, beginnii^s with the upj'kennoet ! How may thi 
locompoeition of be light efTccicd 7 



LIGHT. 45 

ors already named, the violet corresponding with 1, and the 
red with 7. It may be observed by the figure, that the red 
is refracted least, and the violet inost, from the direction of 
the original ray, these two colours terminating the under and 
the upper parts of the spectrum. 

These seven, are called the primary/ colours, since they 
cannot by any known means be again decomposed, or sepa- 
rated into other colours. The whole seven are called the 
solar spectrum. 

The heating powers of these several colours are different. 
Take a sensible air thermometer (fig. 13) and move the bulb 
m succession through all the coloured rays, waiting at each 
for the fluid to rise, or fall. The thermometer will be found 
to indicate the greatest heat in the red ray, next in the green, 
and so on in a diminishing ratio to the violet. 

When the thermometer is moved a little beyond the red 
ray, but in a line with the spectrum, the heat is still greater 
than in the ray itself These heating rays are invisible to 
the eye, and hence it is concluded that there exists in the so- 
lar beam, a distinct ray which causes heat, but no light. 

The illuminating power of each primary ray in the solar 
spectrum, is different from the other. This is proved by 
permitting the spectrum to fall on a large printed sheet, of 
the same sized type, when it will be found, that at the same 
distance, the parts illuminated by some of the rays can be 
read, while those illuminated by others are indistinct. 

Light is capable of being absorbed by certain substances ; 
of remaining in them for a time, and then of being extricated 
unaltered. Such bodies are called solar phosphori. 

Phosphorescence. 

Phosphorescence may be defined, the emission of light 
without sensible heat, or without combustion. 

A considerable number of substances have the power of 
absorbing a quantity of light when exposed to the rays of the 
sun, and of emitting it again, so as to become luminous in 



Whicli ray is most, and which is least refracted, from the direction of the original 
ray 1 What are these seven colours called 7 What are the whole called 1 WTiat is 
said of the heating powers of the different rays 7 Is the greatest heating power in the 
red ray, or beyond it 1 Are the heating rays visible, or invisible 1 How is it proved 
that the illuminating powers of the different rays differ 1 WTiat is phosphorescence 1 
What are solar phosphor! 1 What is said of the power of bodies to absorb and emii 
light 1 



46 PHOSPHORESCENCE. 

the dark. Most substances lose this property in a short time, 
but acquire it arraiii by another exposure to the sun, and thi«a 
may be repeated any number of times. Several substances 
by this treatment become so himinous as to render minute 
objects visible in the dark. Canton's phosphorus is of this 
kind, and may be prepared as follows: Calcine common oys- 
ter shells in the fire for an hour; then select the purest and 
whitest parts, and reduce them to fine powder. Mix three 
parts of this powder with one of sulphur, and having pressed 
the mixture into a crucible, keep it red hot for one hour. 
Then let the crucible cool, and select the brightest and purest 
parts, which cork up in a dry vial for use. 

When til is composition has been exposed for a few minutes 
to the light of the sun, and then carried into the dark, it will 
be sufficiently luminous to show the liour by a watch dial. 

The same property is possessed by compositions called 
Romberg's and Baldwin's phosphorus. The diamond, also, 
possesses this property, as shown by the celebrated experi- 
ment of Dufay, who, having exposed a diamond to the light, 
immediately covered it with wax, and on removing the wajt 
several months afterwards, found that it shone in the dark. 

Some substances phosphoresce by friction ; some by 
scratching, and others by heat. 

That variety of carbonate of lime called dolomite, gives 
light on being rubbed. Loaf sugar mixed with whites of eggs 
and dried, as is done for the frosting of cake, emits a streak 
of light on being scratched with a sharp point. Several va- 
rieties of fluate of lime, and of marble, emit light when 
coarsely powdered and thrown on a hot plate of iron, so as 
to be seen in the dark. 

A piece of tobacco pipe, or a piece of quicklime, when 
heated by the compound blowpipe, or by other means to a 
degree which would only make other bodies red, give out a 
brilliant phosphorescent light, which is so intense as to be 
come intolerable to the eyes. 

Another kind of phosphorescence may be observed during 
the decomposition of certain animal substances. Thus, if a 
small piece of fresh herring, or mackerel, be put into a two 



What \a Canton's phosphorus 7 How is Canton's phosphonia prepared 1 WTiat I 
neccsKiry in onler to make tliis suhmance shine in the dork! How did Dufny confir>« 
lhclif,'f.i in a diamond! Wliat is said of the phoephore.^ccnco of oiiier subeLincce 7 
Wliai in said of the phosphorescence of a piece of tobacco pipe, or quicklime 7 How may 
I piece of fu?h b; made to exhibit phoq^hort^cencc 7 



PHOSPHORESCENCE. 47 

ounce vial of sea water, or into pure water, with a little com- 
mon salt, and the vial be kept in a warm place for two or 
Ciree days, there will then appear a luminous ring on the 
surface of the water, and if the vial be shaken, the whole will 
give a phosphorescent light. 

Light produces very material effects on the growth of all 
vegetables, from the most humble plant, to the tallest tree of 
the forest. Plants, vegetating in the dark, are white, feeble, 
almost tasteless, and contain but little combustible or carbo- 
naceous matter. On exposing such plants to the light of the 
sun, their colours become green, their tastes become much 
more intense, and the quantity of their combustible matter 
becomes greatly increased. These changes are strikingly 
obvious, and beyond all doubt depend on the agency of light. 

Light not only affects the natural, but in many instances, 
the artificial colours of things. In this respect, however, its 
effects appear not to be reducible to any general law, for in 
some instances it destroys, and in others it augments, or even 
creates, the colours of bodies. 

On exposing bees wax to the sun and moisture, its coloui 
is discharged, and it becomes white ; it is also well known 
that the colours of printed goods, and of carpets, are changed 
or faded, by the same influence; and that the former mode 
of bleaching, consisted in exposing the cloth to the united 
influence of light, air, and moisture. 

On the contrary, the colours of plants appear to be exclu- 
sively owing to their exposure to light, and various chemical 
preparations, such as phosphorus, and the nitrate and chloride 
of silver, become dark coloured, and even black, by the influ- 
ence of light. 

Light has also an important and curious influence on the 
crystallization of salts. Make a strong solution of the sul- 
phate of iron, in water, and place it in a shallow dish. Cover 
one half .of the dish with a black cloth, and set it in a darkened 
room, permitting only a single ray of light to enter, so as to 
strike upon the solution in the uncovered part of the dish. 
Thus one half of the solution will be exposed to the light, 
while the other half will be in darkness. After the dish has 
stood in this situation for a day or two, it will be found that no 



How are plants affected by growing in the dark 7 What changes are effected by the 
light of the sun on plants which have grown in the dark 1 How are the artificial colours 
of things affected by light 7 To what do the colours of plants appear to be entirely 
owir;*'^ What substances become dark coloured by the influence of light? 



48 ELECTRICITY. 

signs of crystallization are to be seen in that part of che solu 
tion which has been kept in the dark, while that part which 
lias been exposed to the light will be completely crystallized. 

Another curious fact connected with this subject, is, that 
piants emit oxygen gas, through the influence of the sun's 
light. To make this obvious, fill a tall glass vessel, such as 
a bell glass, with water, and invert it into dnother vessel oi 
water. Then introduce into the bell glass some sprigs of mint 
or any other plant of vigorous growth, and expose the whole 
to the action of the sun. Small bubbles of air will soon ap- 
pear, as though issuing from the leaves of the plant. These 
will, one after another, detach themselves and arise to the 
upper part of the vessel, and on examination, the air thus 
extricated will be found to consist of very pure oxygen gas. 
{Sec Orygcfi.) 

In this experiment, the water serves only as the means of 
collecting the oxygen ; the water itself not being decomposed 
by the plant, but only the air which it contains. The air 
which we breathe contains a quantity of carbonic acid, which 
IS decomposed by the organs of tlie plant, the carbon being 
retained, while the oxygen is emitted. {See Vegetation.) 

Elcctricitij. 

The third imponderable agent is Electricity, including 
Galvanism. 

The ancients knew nothing of electricity as a science. 
They knew indeed that amber and glass, when rubbed, would 
attract light substances: and about the beginning of the eigh- 
teenth century, it was discovered that a certain stone called 
tourmaline, would attract feathers and hair when heated, and 
that some precious stones would do the same when rubbed. 
As an important science, electricity can claim no higher date 
than the age of Franklin. 

Galvanism is of much more recent date than electricity. 
This science owes its name and origin to an accidental dis- 
covery made by Galvani, an Italian, in 1791. Galvani was 
professor of anatomy at Bologna, and his great discovery 
seems to have been owing indirectly to the sickly condition 
of his wife. TIiIg lady being consumptive, was advised to 

IIow la it 8hown thai light has an influence on the crystallization of saltfll How is it 
demoa'rt rated ihal plants emit oxygen paa thrmi!:h \\\o. influence of the sun's light 7 De- 
Hcribe the chemical changes by which plants extricate oxygen ga«. Was electriclly 
kiwwn 10 the ancients as a science 7 What is the dale of electricity afl a science 7 1\) 
what circujnstance doon galvanism owe its origin 1 



ELECTRICITY. 49 

lake soup made of the flesh of frogs, as the most delicate nu- 
triment. One of these animals, ready skinned, happened to 
lie on a table in the professor's laboratory, near which stood 
an electrical machine, with which a pupil was making expe- 
riments. While the machine was in action, the pupil chan- 
ced to touch one of the legs of the frog with a knife which he 
held in his hand, when suddenly the dead animal was thrown 
into violent convulsions.* This singular circumstance excited 
the attention of the sick lady, who was present, and it wa3 
communicated to her husband, who was out of the room at 
the time. Galvani immediately repeated the experiment, and 
soon found that the compulsions took place only when a spark 
was dra^^Ti from the electrical machine, the knife at the same 
time touching the nerve of the frog. He also ascertained 
from further investigations, that the same contractions were 
excited without the agency of an electrical machine, provi- 
ded he employed two metals, such as zinc and silver, one of 
which was made to touch the nerve, while the other touched 
the muscle of the frog. [See Galvanis'm,] It is from such 
a beginning that the now important science of Galvanism had 
its origin. 

Electricity, as an agent, is considered as an exceedingly 
subtle fluid, so light as not to afl!ect the most delicate ba- 
lances, — moving with unmeasurable velocity, and pervading 
all substances. It is therefore its effects on other bodies, 
only, or its phenomena, which it is in our power to examine. 

The simple facts on which the whole science of electricity 
is founded, may be stated in a few words. 

If a piece of glass, amber, or sealing wax, be rubbed with 
the dry hand, or ^A^th flannel, silk, or fur, and then held near 
small light bodies, such as straws, hairs, or threads, these 
bodies will fly towards the glass, amber, or wax, thus rubbed, 
and for a moment will adhere to them. The substances hav- 
ing this power of attraction, are called electrics, and the agen- 
cy by which this power is exerted is called electricity. Some 
bodies, such as certain crystals, exert the same power when 
heated, and others become electric by pressure. 

Although these are simple facts on which the science is 
based, yet electricity exhibits a vast number of curious and 



What is said of electricity as an agent 7 Is it in our po\yer to examine electricity as a 
substance 1 How are we enabled to examine the propenies of this agent? Descnfie the 
Bimple phenomena of electricity. What ai-e electrics? WTiat is electricity? By whal 
process besides friction, do some bodies become electric 1 

5 



ELECTRTCITV. 

17. intercstinf^ phenomena, depending" on the variety 
and kind of machinery, and the quantity of the 
ek'ctrical influence employed. 

When a piece of glass, or other electric, has 
been rubbed, so as to attract other bodies, it is said 
to ])e eir'iicd, and it it is found that most substances 

/are capable of this excitement when managed in a 
peculiar manner. 

The most common are, amber, glass, rosin, sul- 
phur, wax, and the fur of animals. When an excited electric is 
presented towards a small ball, made of pith, or cork, and sus- 
pended by a string, Fig. 17, the ball is attracted to the elec- 
tric, and adheres to it for a moment. And if two such balls 
be suspended so as to touch each other, and the excited 
Pii^. 18. electric bo made to touch one of them, the 
other will instantly recede from the one so 
touched, that is, they will mutually repel each 
other, and remain for a short time in the posi- 
tion sho\\Ti by Fig. 18, If while they are in 
this position, one of them be touched with the 
finger, or a piece of metal, they will again in- 
stantly attract each other, and come together, 
and if suspended apart, will forcibly approach each other, as 
represented by Fig. 19. 

Fig. 19. In the explanation of these phenomena, we sup 
I pose that all bodies are pervaded with the electric 
fluid, but that when in equilibrium, like air and water, 
it produces no obvious eflects, and that it is only 
when this equilibrium is disturbed, or when some 
bodies contain more of the fluid than others, that 
electrical effects can be produced. 

When an electric is rubbed with the hand, or other 
exciting substance, it receives a portion of the electric fluid 
from that substance, consequently the electric, then, has a 
greater portion of electricity than is natural, while the hand, 
or other substance, has less. When two bodies are in diflferent 



When \n an eleoric raid to be excited? Wliai are ihe most common electrical 
What cflTecl does an excited electric produce on a suspended pith ball 7 \Vhat is the 
effect on two piUi balln in contact! When the balls are thrown apart by repulsion, 
what cflTecl is prcxlucetl by touching one of them with the finger 7 Explain these 
phenomena. Are all Ixxlics supposed to be pervaded by the electrical fluid 1 Pup.- 
|K»e an electric is niblicd by the hand, does it in coru«»equence contain more or lea 
cfectriciiy than ljefore7 Whence docc the electric obtain this additional quantity o' 
electricity 7 





i:lectricity. 5i 

electrical states, that is, u'hen one has more, or less than tha 
natural quantity, they attract each other. This is illustrated 
by Fig. 17, where the ball is represented as mo\'ing towards 
the excited electric. 

But when two bodies have each more or less than the natu- 
ral quantity, they repel each other. This is illustrated by 
Fig. 18, where the repulsion is caused by the communication 
of an uncommon share of the fluid from the excited electric 
to one ball, and from this ball to the other, and thus the two 
balls have more than their ordinary quantity of electricity, 
and are in the same electrical state. 

- On touching one of the balls w4th the finger, they again 
attract each other, because the finger deprives this ball of a 
part of its electricity, while the other ball is not aflfected, and 
thus the two balls are thrown into dififerent electrical states. 
This is illustrated by Fig. 19. 

To account for electrical phenomena, Dr. Franklin sup- 
posed, as above stated, that all terrestrial things had a natural 
quantity of that subtle fluid, but that its eflects became appa- 
rent, only when a substance contained more or less than the 
natural quantity, which condition is effected by the friction 
of an electric. Thus, when a piece of glass is rubbed by the 
hand, the equilibriimi is lost, the electrical fluid passing from 
the hand to the glass, so that now the hand contains less, and 
the glass more, than their ordinary quantities. These two 
states he called positive and negative, implying the presence 
and absence of the electrical fluid. If now a conductor of 
electricity-, such as a piece of metal, be made to touch the 
positive body, or is brought near it, the accumulated fluid 
will leave this body and pass to the conductor, which wiL 
then contain more than its natural quantity of the fluid. Bu: 
if the conductor be made to touch a negative body, then the 
conductor -will impart a share of its own natural quantity of 
the fluid to that body, and consequently will contain less than 
ordinary. Also, when one body, positively, and the other 
negatively electrified, are connected by a conducting sub- 
stance, then the fluid rushes from the negative to the positive 
side, and the equilibrium is restored. 



When do bodies attract each other through the influence of electricity? When do 
bodies repel each other through this influence 1 WTien the balls are thrown apart by 
repulsion, why do they attract each other on touching one of them wiih the finger 1 
How are these phenomena accounted for on Dr. Franklin's tkeory % WTiat are the posi- 
tive and negative electrical states! 



52 ELECTRICITY. 

This theory, originally invented by Dr. Franklin, \vill ac- 
count satisfactorily for nearly every electrical phenomenon. 
There is, however, another theory, that of Dufay, which is 
still embraced by some writers. 

This theory supposes that there are two kinds of electrici- 
ty, which are termed the vitreous and resinous, corresponding 
with the j)osilive and negative of Franklin. This tlicn^ry is 
founded on the fact, that when two i)ith balls, or oth<,T light 
I todies, near together, are touched by an excited piece of 
glass, or sealing wax, they repel each other. But if one ol 
the balls be touched by the glass, and the other by tho wax, 
ihey will attract each other. Hence Dufay concluded tliat 
electricity consists of two distinct fluids, which exist together 
in all bodies: that these two fluids attract each other, but 
that they are sejiarated by the excitation of an ekx'tric, and 
(hat when thus separated, and transferred to non-electrics, as 
to the pith balls, tlie mutuiil attraction of the two electricities, 
causes the balls to rush towards each other. 

The electricity corresponding with the positive of Franklin, 
is called vitreous, because it is obtained from glass; Avhile 
the other is called resinous, because it is obtained from wax 
and resin. 

In respect to the merit of those two theories, we can only 
say here, that Franklin's is by far the most simple, and ac- 
counts equally well for nearly every electrical phenomenon- 
Somebodies permit the electrical fluid to pass through them 
without dilficulty. These are called conductors. They are 
the metals, water, and other fluids, except the oils, steam, ice, 
and snow. The best conductors arc gold, silver, plalina, 
brass, and iron. The conductors are non-electrics, that is, 
they show no signs of excitement when rubbed, under com- 
mon circumstances. The electrics are non-conductors, that 
is, they will not conduct the electric fluid from a negative to 
a positive substance, and when excited, this fluid accumulates 
on their surfaces, because they have not the power of coii- 



Docfl Dr. Franklin's lhcor>' account for most of ihc phenomena obeervcd 7 What do 
4hc iKwiiivc and negative Mates imply 1 How does DuJay'e theory differ from Fnuiklin'cl 
How do the vrtrei>ufl and re?(inoUrt electricities of Pniar CGm».<!pond with tlie positive and 
negative of Frankiin 7 Why w ojjc kind o\ electricity called vitiv«Hi8 and ll^e other 
rwinoiis? Wlii.h theory is taid to W. ijic mot-t simple, and therefore to L>e piefemxll 
Wliai l»oilie« permit «ieciricity to |wu»s thnwgh them without diiTiculiy, and wiint are ihey 
CAlled? What arc the bctficuiQduaors] Wliai ia 4lto Jiflcrcno) bclwccn €ouduc4ori oxkl 
uiQ-cooducUMra 1 



ELECTRICITY. 63 

cJucting it away. A body is said to be insulated, when it is 
supported by a non-conductor. A man standing on a stool 
supported by glass legs, or standing on a cake of wax, is in- 
sulated. When one body, or system of bodies, is in the posi- 
tive state, the other part, or system, being contiguous, is in- 
variably in the negative state. If one end of a stick of seal- 
ing-wax, or glass rod, be positive, the other end will be nega- 
tive, and if one side of a plate of glass be positive, the other 
side will be negative. {^See Electricity in Nat. Philosophy.) 

Chemical Effects of Electricity. 

The chemical effects of electricity are most conspicuous 
in that form of this agency known under the name of Gal- 
vanism, but there are many instances in which common elec- 
tricity produces important chemical changes. 

When powerful electrical discharges are passed through a 
glass tube containing pure water, by means of a gold or pla- 
tina conductor, the water is decomposed, and resolved into its 
two elements, hydrogen and oxygen {see these articles,) which 
Fi"". 20. immediately assume the gaseous form. If af- 
terwards the gaseous mixture thus obtained 
be submitted to electrical shocks, the re-union 
—of these elements Avill again be effected, the 
hydrogen will be inflamed, while its combus- 
tion w^ill be supported by the oxygen; the 
gaseous mixture will entirely disappear, and 
water will be formed. 

The method of performing this experiment 
is shown by Fig. 20, where a represents a 
glass tube containing the two gases, and h, c, the tw^o elec- 
trical conductors, the points of which approach so near, as 
to permit the fluid to pass through the gases, from one point 
\o the other. 

To explain the phenomena of the decomposition of the 
water by electrical agency, we have to suppose that the two 
gases are naturally in opposite states of electricity, but that 



Why does electricity accumulate, when a non-conductor is excited 1 When is a body 
eaid to be insulated 7 When one side of a body is positive, in what electrical state will 
the otljer side be ] What are the effects of powerful electrical shocks on water 1 What 
are the effects of the same on a mixture of hydrogen and oxygen 1 Explain Fig. 20, and 
show how the latter experiment is performed. What is it necessary to suppose, in order 
to explain the decomposition of water by electrical agency ) 

5* 



^ 



a 



54 GALVANISM. 

when united to form water, the electricity is in a state of equ'r 
librium. When therefore water is submitted to the power of 
this agent, this equilibrium is destroyed, the mnrative gas or 
oxygen passing to the positive conductor, while the hydrogen 
being in a positive state, passes to the negative conductor. 
Thus the fluid is decomposed, and assumes the gaseous form 
of its constituents. 

The union of the two gases, and the consequent recompo 
sition of water, is simply in consequence of the heat evolved 
by the electrical sliock, as it passes through them. A degree 
of heat bv any other means, sudicient to inflame the hydro 
gen, would produce the same effect. 

Precisely the same phenomena are produced by galvanism, 
both in respect to the dc^composition of water, and the re 
union of its elem.ents. When sulphate of copper is submit 
ted to the action of a j)0werful electrical machine, the salt is 
decomposed, and the metal is revived around the negative wire. 
Other metallic salts undergo the v<;ame dc^com posit ion. 

These effects arise from the different electrical states of the 
elements of which the salts are composed, the positive ele- 
ment beim^ attracted to the negative conductor, and the con- 
trary. It will be seen directly, that the indentity of galvanism 
and electricity is proved by many similar results. 

Galvanisvi. 

It has already been stated, that the science of galvanism 
had its origin from an accidental discovery made by a pupU 
of Galvani, an Italian professor. 

This subject was afterwards prosecuted by Galvani, with 
the most untiring ardor and with great success ; and as his 
discoveries were made known, from time to time, to the scien- 
tific world, philosophers in all parts of Europe vied with each 
other in repeating his experiments, in varying them in all 
possible ways, and in making new experiments to account 
f(»r the cause of the novel and surprising j)henomena they 
observed. An account of these researches belong to th**. 
history of Galvanism, and cannot be included in this concise 
epitome of the science. 



IIow dose electricity acl to rccomposo water from iis two elements ? What ^s sani in 
respect lo galvanism, a.** prcKluciiig ihe same rcsulw as elccirioiiy? When sulplmte of 
copper is Huliiiiiiteil to ihc aciion of elrclriciiy, what phenomena eiLsuc? How is il.ia 
effect on the salts nccounted fori What in said o( the intcrc^ excited among pliiioao 
phoTB by the disjcovcry o( galvanism T 



GALVANISM. 55 

It must suffice here, to state that the discoveries of Profes- 
sor Volta of Pavia, have contributed more towards the pro- 
gress and development of the true principles of this science, 
than the united researches of all his co-labourers. The dis- 
covery and invention of the Galvanic, or Voltaic pile, the en- 
tire merit of Avhich belongs to the Professor of Pavia, re- 
moved all doubt respecting the identity of electricity and gal- 
vanism, and is said to have been the result of deep medita- 
tion and reasoning. Volta' s discovery was published in 1 800, 
and since that time several modifications, and many improve- 
ments in the mode of extricating the galvanic influence, have 
been made ; they all, however, appear to be founded on his 
original invention. 

To make this subject plain, it is necessary to state, that 
Galvani found that w^hen the diiTerent parts of a recent ani- 
mal, as the nerves and muscles, Avere made to touch each 
other, and then the opposite ends of this series made to com- 
municate by means of two different metals, signs of electri- 
city were always apparent. Hence Galvani concluded that 
the different parts of animals were in opposite states of elec- 
tricity, and that the metals only serv^ed to restore the equili- 
brium. On the contrary, Volta maintained that the electrical 
excitement w^as owing to the contact of the two metals, and 
that the animal substances only served to conduct the fluid 
from the positive to the negative metal. And to show that 
this was the true theory of the phenomena, he proved by di- 
rect experiment, that when a piece of zinc, and a piece of 
silver, are placed in contact, and moistened, they are both 
excited, the zinc positively and the silver negatively. Thus, 
when a piece of silver, as a dollar, is placed on the tongue, 
and a piece of zinc under the tongue, and then their two 
edpes made to touch each other, electricity will pass from 
, the zinc to the silver, of which the person will be sensible, 
not only by a peculiar metallic taste, but by the perception of 
a slight flash of light, particularly if the eyes be closed. 

The quantity of electricity evolved by two pieces of metal, 
being exceedingly small, Volta tried the experiment of adding 



"What philosopher next to Galvani, ha.^ made tlie most successful researches on the 
aetiire of galvanism! Who discovered the galvanic pile 1 What is said concerning the 
kbentity of electricity and galvanism? From what expenment did Galvani conclude 
ihstr. the different parts of animals are in different electrical states? By what simple ex- 
periment is it shown that when moistened zinc and silver touch each other, electricity 
passes from one to the other 1 



66 GALVANISM. 

•nany pieces, arrangini^ tliem in pairs, with a conductor be* 
iwtvn them, and found that tlic galvanic influence was in- 
creased in proportion to the number of plates thus combined- 
Such attempts led him finally to construct the Voltaic pile 
already mentioned. This pile consists of a multiplied num- 
ber of galvanic series, terminating at one extremity by a 
positive, and at the other by a negative conductor. 

The conditions necessary for gal\Tinic excitation are en- 
tirely different from those under which common electricity is 
obtainrd. We have seen that electricity is accumulated when 
nn electric or non-conductor is rubbed with the dry hand, or 
with another non-conductor, as a piece of silk or fur. In or- 
dinary galvanic excitation, such substances as are called elec- 
trics are not concerned. 

These substances are all conductors of the electiic fluid; 
one of them a simple conductor, the other two having each 
the additional power of different degrees of electrical, or gal 
vanic excitement. 

These three substances arc usually zinc, water, and cop- 
per, and these, arranged in the order named, compose a sim- 
ple galvanic circle. 

The water, which is mixed with a small quantity of acid, 

not only serves as a conductor of the galvanic fluid, from the 

positive to the negative metal, but also by acting slightly on 

the metals, is the eflicient cause of the galvanic excitation. 

Fig. 21. This arramrement, tocfether with the course of 

the electrical agent from one metal to the other, 

and through the water to the first metal again, 

will be understood by Fig. 21. 

Suppose c to be a plate of copper, and z a plate 
y (^{ zinc, touching each other at the top, and placed 
^*:yX''i in a vessel of acidulated water. Then the action 
^^ o{ the acid will produce an evolution of electri- 
city from both metals, that from the zinc being positive, and 
that from the copper negative. The electrical fluid will 
therefore pass from the zinc through the water to the copper, 
and from the copper by contact to the zinc, and so in a per- 
petual circuit in the direction of the arrows. 



^Vhal is ihc principlt* on whicli the Voltaic pile ia consinicicil 7 What is the difTfer- 
enrc Itetwcon the mihstanccH Oskh! to collrcl electricity, and galvanism 1 Wliai tlirrc 
tuhstanccs u.mally comjKvse a simple paJvanic circle ? What is the u^^e ol the water and 
acid cmploye<l in the cxiricaiion of galvaniaml llxplaiij Fig. 21, au.1 show Uki courbo 
oT the gaivaiiic Huid. 




GALVANISM. 



57 



It is a multiplication of" this principle, that is, by forming 
a series of simple galvanic circles, which composes the gal- 
vanic pile, or pile of Volta, already mentioned. 

This compound galvanic circle is constituted by a series of 
simple circles, so united, as to concentrate the influence of 
the whole at a given point. It may be constructed as follows : 
Provide three glass rods, say of two feet in length each, 
and fix these in an angular direction from each other in a base 
of wood. Provide also circular plates of copper and zinc, 
two or three inches in diameter, about the eighth or tenth of 
an inch thick, and in number proportionate to the power of 
the intended pile. Next cut out the same number of circu- 
lar pieces of card paper, or of woollen cloth, that there are 
pieces of either metal, but less in size. Having thus obtained 
the elements of the pile, its construction consists in placing 
first on the base, or board within the rods, a plate of copper, 
then on this a plate of zinc, and next, on the zinc, a piece of 
the paper, or cloth, dipped in salt water, or acidulated water, 
jp- 22 ^^^^^ forming a single galvanic circle. The same 
^' ' arrangement is observed throughout the whole 
series, that is, copper, zinc, paper; copper, zinc, 
paper ; except in the last circle, or top of the 
pile, which ends with the zinc. Fig. 22, repre- 
sents such a pile, a, h, being the glass rods and 
z, X, the pieces of wood, the upper piece having 
holes to admit the rods in order to make them 
secure. 

Such a series, affords a constant stream of the 
^z galvanic influence, but is always most powerful 
when first constructed, or before the plates become oxidated. 
On this account, after having been some time in use, it re 
quires to be taken in pieces, the plates cleaned from rust, 
and then again reconstructed, when it regains its original 
energy. 

A pile composed of two dozen plates of each metal, will 
give a small shock, which, when taken by the hands, may be 
felt to the elbows. The mode of receiving the shock, is by 
wetting the hands, and then having placed one of them in 




Hew is the pile of Volta CMistructed ? After the frame is made, and the plates ol 
metal and paper prepared, how is the pile then constructed'? When does the pile ope- 
rate mcst powerfully 1 How may the pile, after the plates have become oxidated, be 
made as powerful as at first 1 What is the mode of receiving the shock from the galYanic 
vile 7 



58 GALVANISM. 

contact with the zinc plate, which terminates one end of the 
pile, touch with the other hand, the copper plate which ter- 
minates the other end of the pile. Or these two plates may- 
be touched with a wire, wound with a wet rag and held in the 
pahn of each hand. When experiments are to be made by- 
passing the galvanic influence through any substance, this is 
dune by coniu*cting a wire witli each terminating plate : the 
two moveable ends of the wire being then brought near each 
other, and the substance placed between them, the fluid passes 
from the positive to the negative side, and so through the sub- 
stance. These wires are called the foles of the Voltaic pile. 

Any number of these piles may be connected together by 
making a metallic communication from the last plate of the 
one, to the lirst plate of the other, always observing to pre- 
serve the order of succession from the zinc to the copper, 
and from the copper to the zinc. In this manner a galvanic 
battery is constructed, the power of which will be propor- 
tionate to the number of plates employed. 

The galvanic fluid, it ought to have been observed, is ex- 
tricated only on condition that one of the metals employed 
be more easily oxidated, or more readily dissolved in an acid, 
than the other. Any two metals will form an efTective gal- 
vanic apparatus on this condition, and it is always found that 
the metal having the strongest affinity for oxygen is positive, 
while the other is negative. Thus, any metal, except that 
which has the least affinity for oxygen, of all, may form the 

[)ositive or negative side, by having another metal more or 
ess oxidable than itself, placed in contact with it. 

Copper, in contact Avith zinc, is negative, because zinc is 
most easily dissolved, or has the strongest affinity for oxygen 
of the two. But when copper is in contact with silver, it 
becomes positive, while the silver is negative ; and for the 
same reason silver becomes positive when in contact with 
gold, or platina. The greatest effect is produced, other cir- 
cumstances being equal, when two metals are placed together, 
one having the greatest, and the other the least afliniiy for 
oxygen, as zinc and platina. 

When it is required 10 pass the electricity through a Eaibstance, how is this donel 
What are tlie wires or conductors called 7 How is a ?alvairic battery constructed 1 How 
mii.n the metals dilfer, in rc^jvct to their affinity fur oxygen, in order to evolve calvanismT 
In wliat electrical rtafe is the nieUal which has the stmnpe^i afhnity for oxygen? What 
%\\\ t>c Uie state of copjwr when in contact with zinc 1 Wliai will be the state of copper 
when \u contaa wiih silver or gold ? What niciala will prodiice the grcjaiesi cflcci oo 
Una ar» uunt 7 



GALVANISM. 59 

Since the invention of Volta, a great variety of different 
wethods have been devised, in order to extricate the galvanic 
^uid with greater convenience, or with greater power ; and 
also to modify its action for different purposes. 

Among these inventions, the galvanic trough is one of the 
most convenient and common in this country, though by far 
less powerful in proportion to the surface of the metal em- 
ployed, than several others. 

In this arrangement, the plates of copper and zinc are pla- 
ced with their flat surfaces in contact, and are soldered toge- 
ther on the edges. These plates are then fixed in grooves, 
cut in the opposite sides of a long narrow mahogany box, 
leaving between them narrow intervals. The box of course 
is open on one side, the ends and bottom being made water 
tight, and also the cells between the plates, by cement. In 
fixing the plates, it is obvious that all the zinc surfaces must 
be on one side, or face in the same direction, and all the cop- 
per surfaces on the other side. 
Fig. 23. 

Fig. 23 represents such a 
trough, furnished with con- 
ductors of brass wire, lo, lo^ 
which are fastened to the 
two end plates, or merely 
dipped into the cells. The 
latter is the most convenient method, on account of its allow- 
ing the operator to graduate the shock at pleasure, by inclu- 
ding between the poles a greater or less number of the plates. 
The conductors pass through the glass tubes, a, a, so as to 
allow the operator to handle them without receiving the 
shock himself, and then pass to a glass plate on which the 
subject of experiment is laid. 

When this trough is to be used, the cells between the 
plates are filled with water containing in solution a quantity 
of common salt, or made slightly sour by muriatic, sulphuric, 
or nitric acid. If the water is made warm, the action will be 
much increased. Care must be taken that too much acid be 
not used, for if the action on the zinc plates is such as to 

What method of extricating the galvanic power is said to be among the most con- 
venient 1 Describe the construction of the galvanic trough. In what order must 
the plates of zinc and copper be placed ? Which is said to be most convenient, to 
connect the poles to the plates, or merely to dip them into the cells 7 Wliat are tlie 
uses of the glass tubes a a 7 When the trough is to be used, with what are tne cells 
ailed 7 




OD GALVANISM. 

occasion the emission of bubbles of hydrogen, the g^ilTanic 
action ceases almost entirely. 

After the trough is filled with the water, its edges, and 
also those of the plates, must be wiped dry, and care must be 
taken that it does not leak, otherwise the electric fluid will be 
conducted away by the water. Want of attention to these 
circumstances, will sometimes occasion an entire failure of a 
galvanic experiment. 

Another mode of arranging the gah*anic apparatus, is by 
means of a row of glasses, each containing solution of com- 
mon salt, or a dilute acid. In each glass is placed a plate 
of copper and another of zinc, not in contact, but so con- 
nected by slips of metal, or by wires, that the zinc in one 
cup shall be connected with the copper of the next cup; the 
zinc in the second cup w'nh the copper of the third, and the 
copper of the third with the zinc of the fourth, and so on 
through the series ; except the terminating cups, which con- 
lain only a single plate each, one of copper and the other of 
zinc. This arrangement will be understood by Fig. 24, where 
Fig. 24. a, a, «, are the glasses, z the zinc, x 

the copper, and ic the ^^\Tes by which 
they are connected. The advantage 
is method consists in the exposure 
two sides of the plates to the 
action of the acid ; while by soldering 
the plates, as in the construction of the trough just described, 
one of the surfaces of each metal is protected from the acid, 
and contributes nothing to the efltct. But the bulk of this 
ap))aratus, and the danger of breaking the glasses in case of 
tran.sportation, prevents its general adoption. 

A convenient and more compendious modification of this 
principle lias therefore been contrived, and is called the 
irovgk battery. In this arrangement, the zinc and copper 
plates are united in pairs, as just described, by means of 
slips of metal, which are soldered to each other. Twelve pairs 
of these plates are then fastened to a piece of baked wood, 
being placed at such a distance apart as to fit the cells of a 
trough which contains the water and acid. The trough may 
be made of baked mahogany, with partitions of glass, or 



What caution is ncc«»ary in iT«pcci to the quruiiity of acid, and also in respect to dry- 
4115 ^c cd^cs of the irouch 7 l)r?f rilx* the nuidc of extricating galvanism by mcana ol 
f laas cups. Why is the apjwraius niai!e with cups objectionable ? In wlial is collou 
the troiijli battery, how nrc 0\c plate* nnwrdi 1 




~^" . ". they a; 
, ;-«^-^ of this 

^i '^.j of the 



GALVANISM. 61 

what is better, the whole may be made of earthen, or Wedge- 
wood's ware. 

When this battery is to be used, the cells in the trough are 
partly filled with water, containing an acid or salt in solu- 
tion, and then the plates being connected with the slip of 
wood, are all let doA\Ti into the cells at the same instant, by 
means of a pulley, each cell containing one plate of zinc and 
another of copper. 

Where great power is wanted, any number of these 
troughs may be connected together, by passing a slip of cop- 
per from the positive end of one^, to the negative end of the 
other trough. For the use of a laboratory, this is by far the 
most convenient, as well as the most powerful means of ob- 
taining large quantities of the galvanic fluid, yet devised. 
When an experiment is finished, the operator, in a few min- 
utes, can raise all the plates from their troughs by means of 
pullies, and thus they are suspended, ready to be let down 
again when wanted. The power also, with the same extent 
of surface, is double that of the galvanic trough, where the 
plates are soldered together, since with the present method, 
the entire surface of each metal is exposed to the action of 
the acid. The plates can likewise be more readily cleaned, 
and the whole apparatus more easily kept in repair. 

The Galvanic Battery of the Royal -Institution of Great 
Britain, is constructed on the above plan. It is of immense 
power, consisting of 200 troughs of Wedgewood's Avare, each 
containing ten cells, and receiving ten double plates of cop- 
per and zinc, each plate containing a surface of 32 square 
inches. The whole number of double plates is therefore 
2000, and the whole metallic surface exposed to electricaj 
excitation at the same instant, is equal to 128,000 square 
mches. 

It was by means of this apparatus that Sir Humphrey 
Davy performed his brilliant experiments, and succeeded in 
decomposing the alkalies, and showing their metallic bases. 
(See potash and soda.) 

Chemical effects of Galvanism, It is a singular, and, per- 



In the trough battery, how are the plates of metal brought into contact with the acid f 
What are said to be the advantages of this method 7 Why is this battery more power- 
ful than the galvanic trough in which the plates are soldered together 1 What peculiar 
conveniences has this arrangement 1 What number of double plates does the battery of 
die Royal Institution consist of? What important discoveries did Sir H. Davy make by 
means of this battery ? 

6 



68 GALVANISM. 

haps, unaccountable fact, that the extent of the continuous 
surface of the metals, from which the galvanic fluid is ob- 
tained, has an influence over its effects, when employed for 
various purposes. We should suppose, both from reasoning 
and analogy, that the amount of galvanic action would, in 
every case, be jiroportioned to the number of square inches 
of metallic surface, and that it could make no difference in 
llie result, whether the individual pieces of metal were large 
or small. But experience shows that this is not the case. 
The fflTfCt of a battery composed of large plates, and one of 
small plates of the same extent of surface, is quite different. 
That composed of the large plates having the most intense 
chemical, or heating power, while that consisting of small 
ones has the greatest effect on the animal system. Thus, a 
man can bear with little inconvenience the shock from Mr. 
Children's battery, composed of plates six feet long and two 
feet and a half wide; while he would be stunned, or per 
haps killed, by the shock from the same amount of surface, 
were it divided so as to proceed from plates of only two oi 
three inches in diameter. And yet Mr. Children's battery 
gives the most intensely brilliant caloric effects, while the 
caloric agency of the small plates is comparatively slight 
and insignilicant. 

The decomposing'chemical effects of galvanism have been 
much more extensivelv employed than those of common elec- 
tricity. Indeed, the decomposing power of electricity was 
little known before the brilliant discoveries of Sir H. Davy, 
by means of galvanism ; but since that time, Dr. Wollaston 
has shown that most, if not all of the chemical effects of the 
galvanic battery, may be produced by electricity. 

The decomposition of water by means of eiectricity, was 
effected by the Dutch chemists long before the discovery of 
galvanism. A description of the method of doing this has 
already been given, while treating of electricity. 'I'his seems 
to have been the most important chemical decomposition 
efllected by electricitv, before the discoveries of Galvani and 
Volta. 

Since that period, the science of chemistry has owed to 



Is there any diffcrcnco in the cffccl of a Iwitlery compoectl of large or small nlatep, when 
the extent of their surfaces is ih« same 1 What is the dilRrencfi between llie etfecLs of 
larye am! small plates? Will eleciriciiy proihicc iho siime chcmica! cflects as galvanism ** 
WiL** tlic (lecomixwition of water rtrccieil by eleciriciiy before the discovery of galvoiiism') 
Of wlui 'WO has g.UvaniKwi l>ecn to dicp ' jry 1 



GALVANISM. 63 

»liat of galvanism some of the most magnificent and impor- 
tant discoveries ever made in that science, viz. the decompo- 
sition of the alkalies, and as a consequence of this, other dis- 
coveries of great interest and value. 

One of the most extraordinary facts belonging to the 
agency of galvanism, is the discovery that the elements of 
decomposed bodies follow an invariable law in respect to the 
electrical sides on which they arrange themselves. Thus, in 
decomposing water, or other compounds containing its ele- 
ments, the hydrogen escapes at the negative pole, and the 
oxygen at the positive. In the decomposition of the salts (see 
salts) and other compounds, this law is in every instance 
observed, the same kind of element being always disengaged 
at the same pole of the battery. 

When a compound consists of two gaseous elements, they 
may be readily separated, and each gas obtained separate by 
placing the compound in a bent tube, and then exposing it to 
the galvanic action. 

This simple arrangement is represented by Fig. 25 

Fig. 25. It consists of a glass tube bent as m 

the figure, a small orifice being ground 
at the angle so as to let in the water , 
or instead of this, two tubes may be used 
with their lower ends placed in contact, 
The tubes being filled with w^ater, and 
their lowxr ends placed in a dish of the 
same fluid, the two platina wires pro- 
ceeding from the two sides of the battery 
are passed through corks in the upper ends of the tubes, and 
pushed down, so as to come within about (he eighth of an 
inch of each other. Care must be taken that the adjustment 
be such as to allow the gases as they ascend to come within 
the orifices of the tubes. 

The battery being now set in action, small bubbles of gas 
will be seen to arise from the ends of the wires, but in dif- 
ferent quantities. The tube from the negative wire will 
soon be filled with hydrogen gas, while the other in the same 
time will be only half filled w^ith oxygen. This circum- 
stance arises from the fact, that in forming water, these two 



In the decomposition of water by galvanism, at which pole of the battery doea hydro 
gen always escape 1 Describe the method of decomposing water by galvanism, and ol 
retaining the two gases in a separate state. In perfci'ming this experiment, why is ttia 
tube on the negative side Virzi filled with gas ? 




6*4 GALVANISM. 

nfases combine in the proportion of two volumes of hydrog.jD 
to one of oxy^^en. Of course, therefore, when water is 
decomposed, the volume of oxygen is only half that of hy- 
dro g-en. 

In this experiment, the poles of the battery must be of 
platina, or irold, otherwise, if they are made of iron, or other 
oxidable metal, the oxygen combines with the metal instead 
of being extricated and rising up the tube. 

When neutral salts, whether alkaline, metallic, or earthy, 
such as common salt, blue vitrol, or alum, are exposed to 
the action of a powerful battery, the same law is observed ; 
the acid, which contains the oxygen, goes to the positive 
wire, while the bases being alkalies, metals, or earths, are 
transferretl with the liydrogen (for these salts always contain 
water) to the negative wire. 

But the most surprising effects of the power of this princi- 
ple is exhibited Avhen the compound is placed in cups con- 
nected with the two sides of the battery, and the two consti- 
tuents of the compound are transferred from one cup to the 
other. 

If the solution of any saline compound, such as Glauber's 
salt, be made in water, and placed in two cups, one connected 
with the positive, and the other with the negative side of the 
])attery, then, by making a communication between the cups, 
by means of some moistened asbestos, or cotton, and setting 
the battery in action, the two constituents of the salt will be 
transferred from one cup to the other. 

Fig. 26 will show the situation 
"of the cups, the asbestos, and tho 
galvanic poles for this experiment. 
Both cups contain a solution oi 
Glauber's salt. This salt is com- 
posed of sulphuric acid, soda, and 
water. The cup P is connected 
to tlic positive side of the battery, by a wire, passing into the 
fluid, and the cup N, with the negative side, in the same 
manner. The cups are connected by the moistened asbestos 
passing from the fluid of one to that of the other. When this 
arrangement is completed, and the battery has been some 
time in action, it will be found that the water in the positive 

Jn decomposing the ealLs, what law is observed in respect to the poles, at which iJieU 
clcmrntB arc extricated 7 Explain Fig. 26, and describe how the elements of 'Jie salt ar» 
u-ansfirrL-d from one cup to the oihcr. In which cup is the acid, and in which is iho 
tJkaii fuuud I 





GALVANISM. 65 

cup will have an acid taste, while that m the negative cup 
will have an alkaline taste ; and if the action be continued a 
sufficient time, all the acid contained in the salt will be found 
in one cup, and all the soda in the other. 

Nor does it appear to make any difference in the result, at 
what part of the fluid circuit the salt to be decomposed is 
placed 

Fig. 27. This is proved by 

'placing three cups m 
line, and connecting 
them together by moist- 
ened asbestos, as shown 
by Fig. 27. If the Glau- 
ber's salt, or any other 
saline compound be put 
mto the middle cup, and water into the others, and the two 
galvanic poles be connected with the other cups, P being the 
positive, and N the negative side, then all the acid will be 
transferred to the positive, and all the alkali to the negative 
cup, while the water in the middle cup will remain nearly in 
a state of purity. If the two outer cups be filled with an infu- 
sion of red cabbage, instead of simple water, the operator can 
see the progress of his experiment, since the contents of one 
cup will be turned red by the acid, and the contents of the 
other green by the alkali. 

A phenomenon of a still more extraordinary kind occurred 
to Sir H. Davy, during his experiments on this subject. For 
it was proved that the galvanic action was capable of sus- 
pending the laws of affinity, so that an acid might be convey- 
ed through an alkaline substance, or an alkali through an acid, 
without any combination taking place between them, or either 
might be passed through a cup of infusion of cabbage, with- 
out changing its colour. The three cups being arranged as in 
the last experiment, and connected together by films of moist- 
ened cotton, or asbestos, there was put into the negative cup, 
N, a solution of sulphate of soda, and into the other two cups, 



Describe Fig. 27, and show into which cup the salt is placed, and into which its differ- 
8nt elements are transferred by the galvanic action. What is the advantage of filling the 
iV7o outside cups wi^h infusion of red cabbage ? What extraordinary phenomenon is ob- 
served in respect to the suspension of the laws of affinity by galvanic action 1 Describe 
the experiment by which it was found that an acid or an alkali was made to pass through 
a cup of infusion of cabbage without changing its colour 



66 GALVANISM. 

an infusion of red cabbage in water ; this infusion being one 
of the most delicate tests of the presence of an acid or an 
alkali. After these cups, so arranged, had been for a short 
time placed in the galvanic circuit, the infusion in the positive 
cup became red, and afterwards strongly acid, while that in 
the middle cup continued of the same colour as at first. Thus, 
as the salt was decomposed, its acid passed through the mid- 
dle cup without mixing in the least with the water it con- 
tained, otherwise tts colour would have been changed. On 
reversing the connections, with the poles of the battery, the 
alkali of the salt was transferred to the opposite cup, the so- 
lution of which it tinged green, without in the least aflecting 
the colour of that in the middle cup. 

On placing an alkaline solution in the middle cup, the acid 
was transferred through it, without combination ; and when 
an acid was placed in that cup, an alkali passed through it 
in like manner. 

To account for these singular phenomena. Sir Humphrey 
Dtivy supposed that the elements of compound bodies were in 
different and opposite states of electricity, but that durinp 
their chemical union, an equilibrium existed in tht^se electri 
cal states. This theory we have already mentioned, in ac 
counting for the decomposition of water by common eleclri 
city. But Sir li. Davy believed it to extend in general t( 
all chemical compounds. To explain how the elements o' 
bodies may be in this state, he supposed that each element i5 
naturally possessed with a portion of electricity, whether il 
is in a state of combination or not; and that the elements, in 
this respect, naturally divide themselves into two classes, one 
of which is endowed with positive, and the other with negative 
electricity. In proof of this, it is found as an experimental 
fact, that oxygen, chlorine, iodine, (see the latter article,) and 
acids in general, are naturally negative, while hydrogen, the 
metals, and the metallic oxides, and the alkalies, are naturally 
positive. Thus it appears that bodies having the strongest 
attraction or chemical affinity for each other, are naturally in 
opposite states of electricity, and that the supporters of com- 



Whai arc llic other proofs sliowing that galvanic action Fiisi^cmls the action of affinity ? 
IIow dot\s Sir II. Davv account for ilicsc plicnomcnal In what state of clcc'ricity are 
oxygon, chlorine, icnline, and the acidM generally 7 In what slate are hydrogen and tha 
metals 1 Are Ixxiics having the strongest chcuiiciil alliuity for each otlicr, w l*"* eanitt of 
n opjxxiiic Btaiea of eleciriciiy 1 



GALVANISM. 67 

bustion, oxygen, chlorine, and iodine, are all negatively elec- 
trified. 

From such considerations, Sir H. Davy not only accounts 
for the chemical agency of the galvanic fluid, but also for 
that force called affinity, or chemical attraction, which impels 
bodies of different kinds to unite, and form compounds. Thus, 
oxygen being naturally negative, and hydrogen naturally 
positive, they unite with a force or energy proportional to the 
diflference of their electrical states. 

The decomposing force of the galvanic battery may readily 
be accounted for on the same principle ; for if water be pre- 
sented to any substance of a higher state of positive electri- 
city than its hydrogen, then a decomposition would ensue, 
because the oxygen would leave the hydrogen, and attach it- 
self to that substance for which it had the strongest attrac- 
tion. The voltaic battery produces this effect, by offering to 
the two constituents of water stronger opposite electrical 
energies than these two substances have for each other. Thus, 
supposing the electrical force of hydrogen for oxygen to be 
equal to 3, and that of oxygen to hydrogen to be equal to 3, 
then they would combine with a force equal to 6. But if 
we suppose the galvanic battery to offer to the oxygen a posi- 
tive electrical energy equal to 4, and at the same ^ime to the 
hydrogen a negative energy equal to 4, then it is obvious 
that their combining force wou^ be overcome, and that the 
oxygen would fly to the positive, and the hydrogen to the 
negative poles of the battery, and thus that compound would 
be reduced to its original elements ; and we find that this is 
exactly what happens as a fact, when the water is exposed 
to the galvanic circle. 

This, it must be acknowledged, is one of the most beauti- 
ful theories ever invented, and at the same time agrees with 
the phenomena observed in most energetic chemical changes. 
But there are still some facts for which it does not satisfacto- 
rily account ; nor is it absolutely certain, that in any case, 
chemical attraction is owing to the different electrical states 
of the combining bodies, so that in the present state of know- 
ledge, this theory must be taken only as a probable and high- 
ly ingenious hypothesis. 



How is the decomposing force of galvanism accounted for 1 WTiat is said in re- 
ation to the truth, or probability, of the electrical theory advanced by Sir H. Davy 1 
Ls it certain that in any case chemical attraction is caused by opposite ejectrlCcU 
otatee'? 



68 GALVANISM. 

Heating effects of Galvanism. One of the effects of ^alvj>' 
nic action is the evolution of lieat ; and where the action is 
strong, it is accompanied with light, but not otherwise. 

There is a remarkable difference between the conditions 
necessary to the evolution of heat by galvanic action, and by 
common electricity. In common electricity, there is no pro- 
duction of heat, where the fluid moves through a perfect con- 
ductor, and without obstruction. When it moves along a rod 
of metal, no sensible heat, or light, is evolved, unless the 
conductor is too small for the quantity. But in its passage 
through non-conducting substances, as air, or dry wood, both 
heat and light are a consequence. 

But when galvanism passes through a perfect conductor, and 
the circuit remains entire, and when no light is evolved, there 
is still an elevation of temperature caused by its passage. 

This is readily proved, by making the two poles of the bat^ 
tery meet in a vessel of water containing a thermometer, when 
it will be found that the temperature of the water will soon 
be raised, and if the experiment be continued, the fluid will 
boil by the heat evolved. 

If the battery consists of an extensive series of electrical 
circuits, very powerful calorific effects are produced by the 
passage of the fluid through metallic wires. Iron wire is 
melted and falls do\Mi in globules, and steel wire burns, with 
corruscations too brilliant for the unprotected eye. 

The heating effects of galvanism seem to depend on the 
conducting^ power of the metal employed, the heat being in 
an inverse ratio to the power of the conductor. This is cu- 
riously illustrated by passing the fluid through a wire, or 
chain, composed of alternate portions, or links, of platina and 
silver, soldered together, when it will be found that the silver 
will scarcely be warmed, while the platina will be intensely 
ignited. 

It appears from some experiments made with Mr. Chil- 
dren's great battery, that the heat excited by Voltaic action 
is more intense than that produced by any other means. 



\Vliai is said of ilic heating etfects of gnlvanism 1 Wliat aro the difTcrent condiiiona 
under which heat and light ig evolved by electricity and galvanism! When galvanism 
hi paseed through a p<'rfect conductor, what cirt-ct is produced ) What is the etfect when 
it is passed through water 7 How are metallic wires affected by powerful galvanic action 1 
When galvanism is passed through a chain, the links of which are alternately silver and 
Dlaiina, what is ihe ctTecl on each metal 1 What is said of the power of Mr. Children* 
battcrj 7 



ATTRACTION. 69 

Many substances were fused by it, which were exposed to 
the best wind furnaces without any impression. A piece of 
platina wire, one thirtieth of an inch in diameter, and 
eighteen inches long, became instantly red, then white hot, 
with a brilliancy insupportable to the eyes, and in a few se 
conds was fused into globules. Still this battery had little 
effect on water, or on the human frame, the shock being felt 
no higher than the elbows. 

But still more brilliant effects were produced by the battery 
of the Royal Institution, when pieces of charcoal were attach- 
ed to its poles and then brought near each other. 

This battery, when the cells were filled with a mixture of 
60 parts of water, and one part of nitric, and one of sulphu- 
ric acid, afforded the most splendid and impressive results. 
When pieces of charcoal about one inch long and the sixth 
of an inch in diameter, were placed in the circuit, and made 
to approach each other, a bright spark was seen to issue from 
one to the other, and in a moment the charcoal became igni- 
ted to whiteness. Then by widening the space between the 
charcoal points, a constant discharge continued when they 
were four inches apart, affording a most brilliant ascending 
arch of light, broad in the middle, and terminating in points 
it the charcoal, resembling in shape, two cones, applied base 
Fig. 28. to base. The shape of this 

> brilliant phenomenon is re- 
presented at Fig. 28, where 
. a and b are the poles of the 
battery with pieces of char- 
coal attached to them, and between these the ascending arch 
of light. When any substance was held in this arch, it be- 
came instantly ignited ; platina, one of the most infusible of 
all the metals, melted in it as readily as wax in a candle; 
quartz, sapphire, magnesia, and lime, all entered into fusion; 
and points of diamond and plumbago, rapidly disappeared 
seeming to evaporate with the heat. 

Attraction. 
By attraction is meant that property in bodies which gives 



What effect does this battery have on the human frame % What are the effects when 
pieces of charcoal are placed near each other, in a powerful galvanic circuit? Describe 
Fig. 28. What substances were fused by the battery of the Royal Institution % What is 
tho fourth imponderable agent belonging to our list? 




70 ATTRACTION. 

them a tendency to approach each other, whether they exisT 
in atoms, or masses. Attraction has received various names, 
according to the circumstances under which it is observed to 
act. Thus, that kind of attraction w^hich extends to all kinds 
and quantities of matter, and to all distances, is called aitrao 
lion of gravitation. This attraction extends reciprocally 
from one planet to another, and from all the planets to the 
fixed stars, and is the cause of the orbicular motion of the 
heavenly orbs. It also extends to all terrestrial masses o' 
matter, and is the cause of their weight, or tendency to ap- 
proach the centre of the earth. 

The force of gravitation is directly as the quantity of mat- 
ter, and inversely as the square of the distance. The quan- 
tity of matter being given, and the attracting force at a cer- 
tain distance, say four feet, being known, then this force wdll 
increase, or diminish, as the square of the distance. Thus, if 
one body attracts another, at the distance of two feet, with a 
force of 3G pounds, then at the distance of four feet, its force 
of attraction will be only \ as much, or 9 lbs., and so in this 
ratio whatever the distance may be. {Sec Natural PJiilo 
sojphy. ) 

By attraction of cohesion, or aggregation, is meant that 
force which tends to preserve bodies in masses by acting on 
the particles of which they are composed. This attraction 
is supposed to act only at insensible distances, as when the 
atoms of bodies touch each other, and only when the par- 
ticles of matter are of the same kind. 

Chemical Attraction is that power which forces the particles 
of bodies of different kinds to combine and forma compound. 
This force is also called affinity, because this kind of union 
takes place only between particular substances. Like the 
attraction of cohesion, it acts only at insensible distances, that 
is, the particles of bodies must be brought into the immediate 
vicinity of each other before they will combine. But it dif- 
fers from cohesive attraction in taking place only between 
heterogeneous atoms, or among particles of different kinds of 
matter. Several other kinds of attraction are described, {See 



What is meant by attraction 1 VMiat is attraction of gravitation 1 What are the laws 
of atLractivc force 7 f?upix)HC a body is aitractctl with a force of 36 jx)iinds, at the dis. 
tanceof two feet, wliat wLl the force be at tlie distance of four feet? What is meant by 
attraction of cohcsijon 1 Wliat is chemical attraction 7 How do cohesive and chemical 
attiaciiona dilTer 7 In what ro^jKict is a knowledge of chemical attraction important 1 



ATTRACTION. 71 

Natural Philosophy,) but it is chemical attraction, or affinity, 
which must more immediately occupy our attention here. 

Affinity. Chemical attraction is a subject of the highest 
importance in the study of chemistry, since a knowledge of 
the whole science includes little more than an acquaintance 
with the laws and effects of affinity, that is, of chemical at- 
traction and repulsion. 

We have already noticed that this science is founded on 
experiment, and from deductions arising from facts thus dis- 
covered. Now chemical experiments are only the means oi 
discovering chemical affinities, and a knowledge of these affi- 
nities are the facts on which the whole science is founded. 

By experiment we know that some bodies have an affinity 
to each other ; that is, we know that on presenting them to 
each other under certain circumstances, they will combine, 
and form a third substance, which differs from either of the 
first. We know also by the same means, that other substan- 
ces, when presented together in the same manner, will repel 
each other ; that is, they will not combine, nor can they be 
made to unite so as to form a third substance. 

This kind of knowledge it is impossible for man to acquire 
without actual experiment ; for by no process of reasoning 
could he ever determine before hand, whether two bodies 
would attract or repel each other, any more than he could 
tell what they were composed of by mere inspection. 

We know, for instance, that when we mix acid and water, 
the two liquids unite, or blend together ; now, by reasoning 
from analogy, we should have the same grounds for believing 
Ihat any other fluid would unite with water, that we had for 
believing that an acid would, and therefore that oil and water 
would combine, as well as acid and water. But experiment 
shows, that on this subject, neither reason nor analogy lends 
us the least aid, for, on mixing the oil and water, we find 
that they mutually repel each other, and though blended to- 
gether by force, they again separate as soon as the force is 
removed. 

It is then only by actual experiment that we can decide 



In what does a knowledge of the science of chemistry chiefly consist? What are 
Uie lacts on which the science of chemistry is founded ? How is it known that soma 
Dodies attract, while others repel each other ? Is it possible to gain any knowledge oi 
chemistry, except by experiment 1 WMt reason would there be to suppose, without 
cxpermient, that oil and water would not combine 7 What is the first condition seces- 
eary to e^ect chemical union 1 



72 AFFINITY. 

whether two bodies have an affinity for each other, and con 
scquently whether they are capable of forming a chemical 
compound, or not. 

There arc several circumstances which affect the results of 
chemical affinity, o'V conditions on which its action depends, 
which will be mentioned in their turn. There are also se- 
veral kinds of affinity, which have received different names, 
depending on the conditions under which its action takes 
place. These appellations and conditions will also claim at 
tention as they occur. 

With a few exceptions, the first condition necessary to effect 
chemical combination is, that one or both the bodies should be 
in a fluid state, since however strong the affinity of two bodies 
may be to each other, their particles cannot unite unless they 
are free to move. Hence, to effect the combination of solids, 
their cohesion must first be destroyed either by solution in a 
fluid, or by means of heat. The acids and alkalies have a 
strong affinity for each other, but on mixing them, even when 
in the finest powder, no chemical combination ensues, because 
in all chemical compounds the union takes place between the* 
atoms of the combining substances. 

But on pouring a quantity of water upon such a mixture, 
chemical action instantly ensues, and a third substance, dif- 
fering entirely from the alkali or the acid, is the result of th(.' 
combination. This compound is called a salt. 

In like manner, if zinc and copper be reduced to the finest 
powder, and mixed ever so intimately by mechanical force 
there will still be no intimate union between their particles 
But if heat be applied so as to reduce them to a fluid state, 
they combine with considerable energy, and form a yellow 
alloy, called brass, which differs greatly from the zinc oi 
copper of which it is formed. 

Simple AffiniUj. The most simple cases of affinity are 
afforded by the mixture of two substances which have the 
power of combining with each other, in any proportion. 
Water and sulphuric acid, or water and alcohol, form such 
combinations. What are termed neutral salts, which are 
formed by the union of a pure acid, and a pure alkali, are 
instances of the same kind, only that they do not combine in 
all proportions. In a great variety of instances, after two 



What 13 ncccaeary, in order to nfTect the chemical combination of solids! Why 
will not solids combine as well as flu ids ^ In what manner may copjxjr and zinc be made 
to combine 1 What are the moet eunplc cases of aflinity ^ Give an iUustration of tliia 
•mnity. 



AFFINITY. 73 

85ubslances have combined, when mixed alone, or without 
(he admixture of any other substance, this first union may- 
be destroyed by the intervention of another, or a third sub- 
stance, having a stronger attraction for one of these sub- 
stances than they have for each other. This forms an in- 
stance of what has been termed by Bergman, Elective Af- 
finity. 

Single Elective Affinity, is exercised when one composi 
tion is destroyed, and at the same time another is formed. 
There are many familiar examples of this kind of decompo- 
sition, some of which we witness almost every day. Cam- 
phor dissolved in alcohol or in strong spirits, makes a trans- 
parent solution ; but if water be poured into this solution, it 
instantly becomes turbid, and the camphor separates from its 
connection with the alcohol, and rises to the surface of the 
fluid. This separation takes place because the alcohol has 
a 'Stronger affinity for the water than for the camphor, and 
the turbidness is caused by the insolubility of the camphor in 
water, in consequence of which it takes the solid form. 

Soap is composed of oil, an alkali, and water. The oil and 
water have no affinity for each other, but the alkali has a 
strong affinity both for the oil and water, and consequently 
the three substances unite and form a compound. But if an 
acid be mixed with a solution of soap, the compound is de- 
composed, for the alkali has a stronger attraction for the acid 
than for the oil and water, and consequently the oil is rejected 
and rises to the surface, while the acid and the alkali form a 
"new compound. 

This affinity is called elective, because when one substance 
IS mixed with several others it seems to manifest a choice be- 
tween them, and elects one with which it unites, to the rejec- 
tion of the others. 

It is most probable that every substance has an affinity for 
many other substances. We know indeed that this is true in 
a great variety of instances, since experiment shows that one 
(substance will form several compounds Avith other substances, 
in succession, and that these compounds may in succession 



What is single elective affinity ? Give an example of the exercise of this kind of 
tflrnity. When water is poured into a solution of camphor in spirit, why is the 
camphor separated 1 What is the composition of soap 1 When an acid is mixed 
with a solution of soap, why does the oil rise to the surface 1 Why is this kind of 
•flinity called elective % What is said relative to the attraction of one substance for many 
Qtheirsl 

r 



74 AFFINITY. 

be destroyed by the application of other substances which 
have a stronger aiTinity to the first. 

As an example, suppose sulphuric acid, or the oil of vitriol, 
to be the first substance, or the one towards which several 
other substances have a chemical attraction, but in different 
degrees of force, then a compound formed between the acid 
and the substance having the least afliuity, will be destroyed 
by the substance having the next stronger degree of affinity, 
and this second compound would be decomposed by the sub- 
stance having the next degree of affinity, and so of every 
substance having a stronger attraction for the acid. 

Thus, sulpliuric acid has an affinity for barytes, strontian, 
potash, soda, limt', amvionia, and viagncsia, and the force of 
this affinity is in the order in which they are named; that is, 
barytes has the strongest and magnesia the weakest. A com- 
pound therefore of magnesia and sulphuric acid would be de- 
composed by the addition of ammonia, and one of ammonia 
and the acid, by the addition of lime, and so on ; but none of 
these substances would decompose that formed between the 
acid and barytes, because these substances have the strongest 
affmity for each other. 

No chemical facts appear on first view more simple or in- 
telligible than those which are explained by the operation of 
elective affinity. But we shall find on a more minute exami- 
nation, that this force abstractedly considered, is only one of 
several causes, which are concerned in chemical decomposi- 
tions, and that its action is modified, and sometimes subverteo 
by counteracting causes, to be mentioned hereafter. 

Double Elective Affinity, takes place whenever two 
compounds, each consisting of tw^o ingredients, mutually 
decompose each other, and by a double interchange of these 
principles form two new compounds. We have seen that 
in single elective affinity, one new compound is formed by 
the addition of a single substance, while the ingredient thus 
rejected remained imcombined, or alone, in the solution. 
Thus, when lime is added to a compound of magnesia ana 
sulphuric acid, the lime and acid unite, while the magnesia 



What are ihc Bub.stan*es named, a.«? havinc an ainnity for sulphuric acid, and in what 
OTikr is the force of this aflmiiy wiljj resjxrt to the substances 7 Suppose soda and su* 
phuric acid to be combined, wiiich of the eubsiances named would decompose the com 
pound 1 Whicli of the Riib-^tances named would decoinpose sulphate of barytes 7 When 
doM double clectire ftfTinity take place] 



AFFINITY. 75 

IS rejected, and remains solitary in the solution, having no- 
thing on which to bestow its affinity. 

In double elective affinity, an interchange of the principles 
belonging to each compound is effected, and thus the old 
compounds are destroyed, and new ones formed ; and it is 
curious and interesting to observe the consequences, of what 
we should call the likes and dislikes of the particles of mat- 
ter for each other, were they animated. 

It often happens, that a compound of two ingredients can 
not be destroyed by the application of a third, or fourth in- 
gredient, separately ; but if the third and fourth be combined, 
and then the two compounds be brought into contact with 
each other, decomposition and interchange of principles will 
ensue. Thus, sulphate of soda is composed of soda and 
sulphuric acid, and is the substance called glauber's salt. 
Now when lime is added to a solution of this salt, there en- 
sues no decomposition, because the soda attracts the acid, 
more strongly than the acid attracts the lime. If muria- 
tic acid be added to the same solution, there still follows no 
decomposition, because the sulphuric acid has a greater 
affinity for the soda, than the soda has for the muriatic acid. 
But if the lime and muriatic acid be previously combined, 
forming a muriate of lime, and this compound be added to 
the solution of the sulphate of soda, then a double decompo- 
sition follows, and two new compounds are formed out of the 
old ingredients. The lime of the muriate of lime, and the 
sulphuric acid of the sulphate of soda, having stronger af- 
finities for each other, than the first has for muriatic acid, 
or the second for soda, mutually abandon their old connec- 
tions, and having combined with each other, form a new com 
pound under the name of sulphate of lime. The soda and 
muriatic acid being thus rejected, and their former unions 
dissolved, they combine themselves anew, and form another 
compound, known under the name of muriate of soda, or 
common salt. These changes will perhaps be better under- 
stood ly the diagram, which follows. 



In this kind of affinity, how many old compounds are destroyed, and how many new 
one-s formed at the same time 1 Why does not lime decompose sulphate of soda ? Why 
does not muriatic acid decompose sulphate of soda ? What are the chemical changes 
effected when muriate of lime is added to a solution of sulphate of soda 1 What are the 
names of the new oompounds formed by the decomposition of sulphate of soda, and mu. 
riate of lime 1 



76 



COHESION. 

Muriate of Soda. 



Sulphate 

of 
Soda, 



Soda. 



Muriatic acid. 



Sulphuric acid. 



Lime. 



Muriate 
Lime. 



Su Iphate of Li m c. 
On the outside of the vertical brackets are placed the name.^ 
of the original compounds, sulphate of soda and muriate of 
lime, and above and below the diatrram those of the new com- 
pounds. The upper line is strait, to indicate thai the muri- 
ate of soda remains in solution, while the middle of the lowei 
one is directed dowTiward, to show that the sulphate of linitj 
is precipitated, or falls to the bottom of the vessel. 

Causes which counteract or modify the effects of chemical 

affinity. 

It has been stated that the effects of chemicd action are 
often modified, or even subverted, by counteracting causes. 
The principal causes which have a tendency to counteract 
chemical combinations are cohesion, quantity of matter, elas- 
ticity, and gravity. 

Cohcsio7i. By cohesion, we mean that attractive force by 
which the particles of bodies are kept together, and in conse- 
quence of which, masses are formed. This force may modi- 
fy, or entirely counteract that of chemical aUraction ; for the 
more strongly the particles of any substance are united, the 
greater the obstacle to a chemical union Avith those of other 
bodies, because the successful effects of affinitv depend on a 
mutual penetration of particles. Hence the formation of che- 
mical compounds, with some exceptions, requires that at least 
one of the ingredients should be in the state of a liquid, so 
that the particles of each should have free mutual access 
Where the affmities are strong, and the cohesion slight, the 
union is effected with considerable energy, under such cir- 
cumstances. Thus, masses of carbonate of ammonia, of con- 
siderable size, will be dissolved by nitric acid ; but when the 



ExjJlain the diagram illustrating theac changes. What are the principal causes which 
promote or counteract chemical changes ^ Whai is meant by coliesion 7 How doc* 
cohesion preTonl solution 1 



COHESION. 77 

force of cohesion is great, it is a strong barrier to the opera- 
tion of affinity. Thus, a mass of carbonate of lime, or mar- 
ble, will remain for days in an acid, when, were it reduced to 
powder, it would be dissolved in a few minutes. 

In all such cases, therefore, mechanical division is required 
before rapid solution, or intense chemical action, can be ef- 
fected. Cohesion being thus overcome, solution is readily 
accomplished, because the solid now presents a greater extent 
of surface to the action of the fluid. 

Heat is another means of counteracting the cohesion of 
bodies, the repulsive power of caloric being indeed the great 
opposing force of that of cohesion, and provided its quantity 
be proportionate to the force of attraction, will so overcome 
It as to render all solid bodies liquid. Different substances, 
*t is obvious, require different degrees of heat for this purpose. 
Thus, the cohesive force of such bodies as are called liquids, 
is so counteracted by the heat of ordinary temperatures, as to 
make their particles easily moveable among each other, a 
circumstance on which their liquidity depends. But many 
of these substances, such as water and oil, by the abstraction 
of heat, become solids, because then the repulsive force of 
caloric becomes less than the attractive force of cohesion. 
On the contrary, in bodies which we term solids, the attract- 
ive force of cohesion is greater than the repulsive power of 
caloric, and hence at all ordinary temperatures, their parti- 
cles are fixed and immoveable among themselves, a circum- 
stance on which their solidity depends. 

We have stated that the exercise of affinity depends on the 
state of the substances concerned, and that in general, one of 
them must be in a fluid state. In most instances, solution is 
effected in some liquid, as an acid, alcohol, or water. But 
to produce metallic alloys, the metals must be brought to a 
li({uid state without changing their properties, and this can 
be effected only by means of caloric. For this purpose, it is 
only necessary that one of the metals, viz. that requiring the 
highest degree of heat, should be melted, and the other thrown 
into this in small pieces. 

Quantity of matter. Experiment teaches that quantity of 



Why will the same substance in powder enter into solution more readily '.han when in 
fie massl What is the opposing force to cohesion? What is the cause of fluidity in 
:»oJies7 How might all bodies be made fluid 1 Why does water become solid when cal* 
•jfio is abstracted from it 1 On what does the solidity of bodiee depend? What ia tur 
only i^eans by which metallic alloys can be produced % 



7d COHESION. 

matter exerts an important influence over chemical decom- 
positions and solutions. Thus, we know precisely how much 
fiulphuric acid, for instance, —ill neutralize a given quantity 
of potash, when in a free state. But if the same quantity of 
potash be first combined with nitric acid, forming nitrate of 
potash, or saltpetre, then more of the sulphuric acid is re- 
quired to detach this quantity than before, probably because 
some force is employed to destroy the union previously exist- 
ing between the nitric acid and the potash, and also because 
the afhnity of the two substances for each other diminishes 
when both are nearly saturated. 

In making a solution of a metai in an acid, it may be ob- 
served, that the chemical action is much more energetic at 
the beginning of the process then aUerwards, and that if no 
more acid be added, than is just sufficient to dissolve the me- 
tal, the action finally becomes so feeble as to require a day or 
two to complete the combination. But if, in this state, more 
acid be added, the action again becomes brisk, and the metal 
is soon dissolved. 

Elasticity. Cohesion being found an obstacle to the exer- 
cise of affinity, it might be expected that the contrary state, 
that is, the absence of cohesion, would facilitate chemical 
combinations; but experiment determines otherwise. In the 
elastic fluids, such as the gases, and common air, cohesion 
may be considered as entirely wanting. But bodies of this 
kind, though having a strong affinity to each other, show 
little disposition, under ordinary circumstances, to combine. 
Thus, oxygen and hydrogen, though in different electrical 
states, may be mixed together in the same vessel for any pe- 
riod of time, without the least symptom of combination. The 
reason of this, is probably owing to the distance of their par- 
ticles, which prevents that near approach to each other, requi- 
red to come within the sphere of mutual attraction; for if the 
two gases be subjected to pressure by means of the little in- 
strument called a fire pump, Fig. 11, they unite with explo- 
sive energy. 

The elastic property not only opposes the chemical union 
of bodies, but is often an agent by which their decomposition 



What is Baitl of the influence of quantity of matter on chemical combinations ? Ex- 
plain how quantity of matter is illustrated by the solution of a metal in an acid. Docs the 
elastic state facilitate chemical combinations? What is the most probable reason*? tha 
puses havinu an affinity for each other do not unite, when mixed under ordiiwry circun: 
fiancee 1 How may oxygen and hydrogen be made to combine 1 



CHEMICAL CHANGES. 79 

IS effected when exposed to the influence of caloric. Thus, 
substances containing a volatile and fixed principle, are 
sometimes decomposed by heat alone, because the repulsive 
force of caloric removes the elements of the compound be- 
yond the influence of mutual attraction, and the volatile ele- 
ment makes its escape in consequence. Many of the salts, 
composed of an alkali, or a metal, and an acid, and water, 
are readily decomposed by heat alone. The water is first 
turned to steam, and escapes by its elasticity, leaving the salt 
opake, and as the heat is raised, the acid is converted into 
vapour, and escapes in the same manner. 

On the same principle, oxygen is obtained from manga- 
nese, from nitre, and several other compounds, where it 
exists as a principle. 

Grojvity. When the difference between the weight of the 
two bodies is great, this circumstance opposes their chemical 
combination. Thus, when common salt is thrown into water, 
it sinks to the bottom, where the water soon becomes satura- 
ted, and will dissolve no more; but if the w^ater be agitated, 
the whole will soon dissolve. It is found, also, that metals 
differing widely in their specific gravities, when melted to- 
gether, do not mix equally, unless they are stirred, because 
the heavier metal settles to the bottom. 

Changes produced hy Chemical Combinations. 

By chemical combination is meant a union between two or 
more substances of different kinds, so intimate that they can- 
not again be separated by mechanical means. Thus, if clay 
or chalk and water be mixed, the mixture will for a time be 
turbid, or opake, but if suffered to stand for a day or two, the 
clay or chalk will settle to the bottom of the vessel, and the 
water above will become transparent. But if water be mixed 
with an acid, or with a salt, or with sugar, the union becomes 
permanent, nor will rest, or filtration, or any other mechani- 
cal means, separate either of these ingredients from the wa- 
er. Hence, the distinction between jnechanical mixture and 



How does caloric act to separate a volatile from a fixed principle 1 How is the decom- 
position of a fluid eflTected by heat 1 What is said of gravity in opposing chemical 
union 1 How does common salt, in water, illustrate this principle 1 What is said of the 
combination of metals in this respect 1 What is meant by chemical combination 1 
What is the distinction between mechanical mixture and chemical union 1 Why will 
not chalk and water combine permanently 1 When water and sugar are mix:ed, why 
does not the sugax setUe to the bottom of the ressei t 



80 CHEMICAL CHANGES. 

chemical union. In the first, no affinity between the sub 
stances exists, and therefore no union takes place, and tht^ 
chalk or clay falls to the bottom of the vessel. In the second, 
there is a combination between the particles of which the 
substances are composed, owing to the affinity existing be- 
tween them, and hence they are not separated, except by a 
stronger force than that of the existing affinity. 

The changes that accompany chemical action, are in some 
proportion to its intensity. In the instances above named, 
where water is mixed with a small quantity of acid or salt, 
this action is feeble, and the sensible changes produced in- 
considerable, being only a slightly acidulous, or saline taste, 
given to the water. But in cases where the chemical action 
is intense, the changes produced in the combining substances 
are often great in proportion. Thus, when the two gases, 
oxygen and hydrogen, are burned together, their combination 
is attended with most intense chemical action, by which the 
highest degrees of heat are evolved, and at the same time 
the change produced is no less than the condensation of two 
elastic gases into the fluid water. 

Many substances which are highly corrosive, in a sepa 
rate state, become mil(i^ and lose all their acrid qualities by 
combination with each other. Sulphuric acid and potash, 
for example, are highly caustic substances. They both act 
with great energy on animal and vegetable bodies, producing 
decomposition and total destruction of texture. The acid 
turns the blue colors of vegetables to red, and the alkali turns 
these colors to green. But on mixing these substances to- 
gether, they entirely destroy the caustic qualities of each 
other, and there results a solid compound, called sulphate oj 
potash, which is mild to the taste, and neither acts on animal 
or vegetable bodies, nor changes the colors of the latter. 
This is called a neutral salt, because the substances of which 
it IS composed, thus neutralize the active properties of each 
other. 

When the opposing properties of chemical agents are thus 
destroyed by combination, they are said to saturate each 
other, and it is found that the acrid and caustic qualities of all 



Is there any proportion b^.ween the intensity of chemical action and the changes pro 
duced thereby 1 What illuc-trations of this law are given 7 What effect does combina- 
tion sometimes have on the corrosive properties of bodies 1 Give an illustration of this 
effect 7 What is the composition of sulphate of potash 1 What is a iieutral salt 1 Whea 
a!« substances eaid to eaturate each othter } 



AFFINITY. 81 

the acids and aUalies are weakened in proportion as one is 
added to the other, until the point of saturation is attained, 
when the compound becomes neutral, and is not affected by 
a further addition of the acid or alkali, which forms a part of 
its composition. 

A chsLXige of bulk is also in many instances the result of 
chemical union, so that the two bodies after combination, do 
not occupy the same space as before. Thus, when a pint of 
sulphuric acid is mixed with a pint of water, the chemical 
action is so great as to raise the thermometer above the boil- 
ing point, and the resulting compound will not measure twxt 
pints as before the mixture, but considerably less. 

When zinc and copper are fused together, the resulting al- 
loy has a specific gravity greater than the medium specific 
gravities of the two metals, showing that their bulks are di- 
minished by the union. The same happens when alcohol 
and water are mixed ; and in general it is found that the re- 
L-ulting body after chemical combination has a greater speci- 
fic gravity than the mean of its components. 

Another change often produced by the exercise of affinity, 
:s that of colour. The alloys of any Uxo metals do not ex- 
hibit the medium of their two colours. Thus the white me- 
tal, zinc, and the red one, copper, when melted together, form 
the yellow compound, brass. The colours of the metallic ox- 
ides differ according to the quantities of oxygen they contain. 
The black oxide of mercury contains 200 parts of the metal 
and 8 parts of oxygen, while the same quantity of the metal 
combined with 16 parts of oxygen, forms the red oxide of 
mercury. We have already had occasion to notice, that blua 
vegetable colours are changed to red by acids, and to green 
Dy alkalies ; and in addition to this, we may state generally, 
that all vegetable colours are changed, more or less, by the 
application of these agents. -"' 

There is still another change, which is the effect of chemi- 
cal affinity, and is often highly important ; this is the change 
of form. Of this change chemistry exhibits a great variety 
of examples, many of which are highly curious and interest- 



What is said of change of bulk as a result of chemical action ? Suppose a quantity oi 
water and sulphuric acid are mixed, will they occupy the same bulk that they did before 
he mixture 1 Will the bulk be greater or less than before 7 In chemical combinations, 
s the resulting body more or less dense than the medium density of its components 7 
What is said of the change of colour produced by chemical combinations 1 Is change o( 
form ever effected by chemical combinations ? 



82 AFFINITY. 

ing. ' Thus, if a saturated solution of muriate of lime in wa- 
ter, be mixed with a small quantity of sulphuric acid, the 
two fluids immediately become a solid. This change is pro- 
duced by the exercise of affinity. The muriate of lime is 
composed of lime and muriatic acid, and of this salt, water will 
dissolve a large quantity and still remain fluid. The sulphu- 
ric acid has a stronger attraction for lime than the muriatic 
has, and the sulphate of lime is nearly insoluble in water. 
When therefore the former acid is added to the solution, a 
sulphate of lime is formed, which in a spongy form occupies 
the whole vessel. On the contrary, if equal parts of alum 
and acetate, or sugar of lead, be rubbed forcibly together in 
a mortar, they form a compound mass which is nearly fluid. 
The cause of this change from the solid to the semi-fluid 
state, is also easily explained. The alum and sugar of lead 
contain a quantity of water, called the water of crystallization. 
When they are forcibly rubbed together, the elements of which 
they are composed, unite in consequence of mutual affinity, 
and thus the water of crystallization is set free, and occasions 
the partial fluidity of the mixture. The great changes which 
the two gases undergo in the formation of water, have al- 
ready been mentioned. Similar changes, so far as respects 
the condensation of elastic fluids and liquids, are phenomena 
which are frequently witnessed in experimental chemistry. 
Thus, water absorbs about 500 time its own bulk of the gas, 
called ammonia, which is in this manner condensed, and 
forms a part of the liquid. The compound thus formed is 
known by the name of s'pirit of harUhorn. Quicklime, in the 
process of slacking, absorbs a large quantity of water, w^hich 
by this combination becomes solid, and forms a part of the 
dry lime. 

In the formation of the gases, on the contrary, there is an 
immense increase of bulk. When water is decomposed and 
made to assume its elementary gaseous form, there is an in- 
crease of bulk nearly equal to 2000 volumes. That is, a 
cubic inch of water contains 662 cubic inches of oxygen, and 
1325 cubic inches of hydrogen; thus the volumeois in- 
creased 1987 times by the decomposition. The explosion 



How is the change of form accounted for when sulphuric acid and muriate of lime are 
mixed 7 How is the change of form explained, when alum and acetate of lead are for- 
cibly mixed? What is said of the condensation of ammonia by water, and the conden- 
sation of water by slacking lime 7 How many times more bulky are the gases of which 
water is composed, than water itself 1 



AFFINITY. 83 

of gun powder is another example of the vast increase of 
volume by chemical decomposition. 

Force of Chemical Affinity. Although it is ascertained, 
ny means already described, that the affinity of one body for 
a number of others, is not of equal force, yet we are ignorant 
how much difference there is in the forces of these different 
degrees of affinity. 

The only means of deciding this question is to observe the 
tendency which several substances have to unite with the 
same substance, under similar circumstances. Oxygen, for 
instance, as a universal agent, might be selected as a stand- 
ard, and the force of affinity between this and other bodies 
be estimated by their degrees of oxidation under the same 
circumstances. We know that there is an immense differ- 
ence between the forces with which different bodies attract 
this principle. Some of the metals, for instance, absorb 
oxygen with such avidity, that they cannot be preserved in 
their metallic state when exposed to the atmosphere, even 
for a short time ; while O'thers have so little affinity for this 
principle, that they cannot be oxidated without the most ener 
getic means. Thus, potassium (see this word) attracts oxy 
gen with such force as to decompose water, at common tem- 
peratures, by absorbing it from the hydrogen ; while the 
affinity of platina or gold for this principle is so weak as not 
to attract it at all, except at the highest degrees of heat, or 
from acids which impart it most easily. 

We may constantly observe the effect of the different 
forces with which several metals attract oxygen in the com- 
mon affairs of life. Thus, iron and lead, when exposed to 
the moisture of the atmosphere, soon tarnish, and after a 
time, by the absorption of oxygen, their surfaces become 
covered with rust, or the oxides of iron and lead. But silver 
and gold when exposed in the same manner, continue bright 
and untarnished for years, as may be observed in the points 
of lightning rods, and the gilded vanes and balls of church 
steeples. This difference can only arise from the different 
forces with which these metals attract the oxygen of the at- 
mosphere. 

There is no department in chemistry, either as a science, 



Hew might the force of affinity be ascertained 1 How do we know that there is a great 
difi'erence between the forces with which bodies attract oxygen 1 How is this difference 
Illustrated 1 How is it shown that iron and lead attract oxygen with greater force thaii 
eilyer and gold ? 



84 niorouTiONs. 

IT an art, which so mucli needs tlie investigation of able men 
as this. Tables of alFinity, showing at once the force of at- 
traction between difierent chemical elements, would enable 
the in(|uirer, without further experiment, to decide what sub- 
stance would decompose any given compound, and therefore 
how to separate, or combine, the difierent principles of bodies 
for a vast variety of purposes. Tables to a very limited ex- 
tent have already been constructed for such ])urposes, but the 
dilficulty and magnitude of this subject seems to have deter- 
red the more modern chemists from engaging in this exten 
sive department of the science. 

Indrfinite and Definite Proportions. 

It is ascertained by experiment that some bodies unite m 
unlimited, or indefinite proportions, while others combine in 
proportions which are always limited, or definite. 

The discovery of the laws of definite proportions is one of 
the most important and wonderful among the great and bril- 
liant achievements in modern chemistry. It is sufficient of 
itself to convince any reasoning mind, that order and system 
pervade the universe, and that the minutest atoms of matter, 
and the vast orbs that move round the heavens, are equallj 
under the control of the invariable laws of the Creator. 

Indefinite proportions. When we mix water and alcohol, 
or water and any of the acids, they unite in any proportion. 
Thus, a drop of acid will combine with any quantity of water, 
-md water will unite in the same manner with alcohol, or acid. 
Tliis principle may be tested by direct experiment; for if a 
gallon of water be tinged blue by a vegetable colour, a few 
Jrops of sulphuric acid will turn every drop in the gallon to 
a red colour, thus proving, that this small quantity of acid has 
dififused itself through the whole mass. By similar experi- 
ment it can be shown that a small quantity of water will dif- 
fuse itself through a large quantity of acid. These examples 
prove that some bodies combine in unlimited proportions on 
both sides. 

Other con^binations appear to be limited on one side, and 
unlimited on the other. Thus, common salt, and other saline 
substances, Avill dissolve in water in any proportion short of 



What woulvl be ihc use of Uihlcs, showing the force of attraction between diiferejH 
cfieiuical element.s 1 What is saiil of the disc;nery of the laws of definite proporiiooa 7 
What suljstanccs are mcnlioncil, wliicli conil«ine in unrunited proixiriions? 



PROPORTIONS. 85 

liie point of saturation, after which, if more be added, it will 
fall to the bottom of the vessel and remain solid. The great- 
est proportions in which water and common salt combine, 
are those of 100 of the former, with 40 of the latter; but the 
smallest quantity of salt will diffuse itself through the largest 
quantity of water, and the probable reason why salt does not 
unite with water in every proportion, is, that its cohesion 
resists the feeble affinity of the fluid after it becomes satura- 
ted. 

In all cases where bodies combine with each other in eve- 
ry proportion, or where the proportions are limited on one 
side, and indefinite on the other, the force of affinity by which 
such compounds are formed is feeble, and the compounds 
themselves often differ but little from the original ingredients. 
Thus, alcohol and water combine in all proportions, but the 
union produces only a modification of the qualities of each, 
the degrees of which depend on the proportions of the mix- 
ture, and the force of affinity between them is so weak, that 
distillation, by a gentle heat, entirely destroys their union. 
Solutions of the salts, sugar, acids, and many other princi- 
ples, are examples of the same kind ; a moderate heat, and 
sometimes evaporation, without heat, will dissipate the water 
and leave the other ingredients in their former state. 

In these, and a great variety of other instances, although 
the force of affinity is slight, still there is a wide difference 
between such compounds, and mere mechanical mixtures, 
since the latter are separated by rest, while the ingredients 
of the former are not separated by rest, filtration, or any other 
mechanical means. 

These solutions, or combinations, formed by feeble affini 
ties, resemble mixtures in respect to the slight changes which 
their ingredients undergo by uniting, while they resemble 
chemical compounds in respect to the inseparable nature of 
(he union, by mechanical means. 

The writer of the article Chemistry, in the Library of 



How is it proved that a few drops of acid will diffuse itself through a large quantity A 
^ater 1 What bodies combiuc in limited proportions on one side, and unlimited propor- 
dons on the other ? In what proportions do water and common salt combine ? In cases 
where bodies unite in all proportions, is the force of affmity strong or weak 1 What 
are the substances mentioned, which unite in all proportions 1 In what respect do com- 
biiAtions, formed by feeble affinities, resemble mixtures, and in what respect do they 
tesfcmble chemical compounds? What are these slight combinations called in the Li 
fcrarjr of Ueefvl Knowledge 1 

8 



86 PROPORTIONS. 

Useful Knowledge, has called such slight combinations Che- 
mical mixtures, in order to distinguish them from compounds 
formed by energetic affinities, and which come within the law 
of definite proportions. 

But as the student will find "in most books on this subject, 
that mixtures are distinguished from compounds only by the 
means necessary to separate their ingredients, we have 
thought* best, at present, to continue the same division ; at 
the same time, having it distinctly understood, that the uni- 
versality of definite proportions, applies only to energetic 
combinations. 

Definite Proportions. 

By definite proportions in chemistry, it is meant that the 
ingredients, or elements of chemical compounds, unite with 
each other in certain proportions only ; and that these propor 
tions in the same compound, are under all circumstances in- 
variably the same. The proofs of this doctrine are estab- 
lished by experiments conducted with the most rigid 'exact- 
ness, and it is true, beyond all controversy. 

The subject of definite proportions may be conveniently 
treated of, under three several propositions or laws, it being 
understood that the proportion of hydrogen in water repre- 
sents unity or 1, and that this is the common unit to which 
all the other numbers refer. 

First, The composition of all chemical compounds is fixed, 
and invariable. 

Experiment shows that some bodies combine in only one 
proportion. Thus, there is only one compound of zinc, and 
oxygen, called the oxide of zinc. Other bodies combine in 
two proportions. Thus, there are two oxides of copper, one 
of which is composed by weight of 1 proportion of oxygen, 
and 8 of copper, and the other, 2 of oxygen, and 8 of copper. 
Other bodies again combine in three, four, five, or even six 
proportions, the latter being the greatest number of compounds 



What is meant by definite proportions in chemistry 1 What is the first law of definite 
proportions 7 What two substances combine only in one proportion 7 What two sub- 
Btances are mentioned which combine in two proportions, and what are these propor- 
tions 7 What number c/ compounds are known to be formed by two elements'? The 
proportions of any chemical co7*npoand beip ; de*mite, what would be the effect of chajjg- 
Ing these proportions 1 



PROPORTIONS. 87 

known to have been formed by any two ^bstances, within 
the limits of definite proportions. 

The proportions of any given compound being invariably 
the same, it follows that its characteristic properties depend 
on these proportions, and that if these proportions are changed, 
the compound will contain new properties, and therefore a 
new substance is formed. As an example of the change 
produced on the compound, by a different proportion of one 
of its constituents, we will cite mercury and chlorine, (see 
chlorine.) These two substances unite in two proportions, 
the first of which is composed of mercury 200, and chlorine 
36. This forms the well known medicine called calomel, and 
is sometimes given in doses of a tea-spoonful at a time, with- 
out injury. The other is composed of mercury 200, and 
chlorine 72, being one more proportion of chlorine, than is 
contained in the calomel. But the two compounds in their 
sensible qualities are entirely different, the latter being one 
of the most active and fatal of poisons, and is known by the 
name of corrosive sublimate. Thus two substances uniting in 
one proportion, form^ a compound which is comparatively 
mert, while in another proportion they form one of the most 
virulent poisons known. Nor is there any medium, or half 
way union between these bodies ; they combine in these two 
proportions or not at all. For, suppose 200 parts of mercury 
should be exposed to the action of 40 parts, by weight, of 
chlorine, then the mercury would combine with 36 parts of 
the gas, and no more, leaving the other 4 parts remaining un- 
touched. And so, on the contrary, if 210 parts of the meta. 
be exposed to the action of 36 parts of the gas, then the gas 
will combine with 200 parts of the mercury, while the 10 
parts would remain uncombined. 

In all energetic combinations the proportions of the com- 
bining substances are limited in the same manner, though 
the proportions themselves are exceedingly various. Indeed, 
it appears that the law of limited proportions, is as universal 
and as permanent as the law of gravitation itself, and that 
its doctrines, so far from being founded on the theoretical 
opinions of men, are in truth based on a general, but more 
recently discovered law of nature. 



What example is given of the difference between compounds formed of one and two 
proportions of the same elements 1 What is said concerning the combination of mercury 
and clilorine in other proportions 1 Will 40 parts of chlorine unite with 200 parts of 
mercury 7 On what ia it said the truth of the law of definite proportions is founded 1 



08 PROPORTIONS. 

Second. When two substances unite in more than one pro- 
portion, the second or third proportions are multiples of ih& 
first, by a whole number. 

This very remarkable law applies in every case where 
bodies unite with each other in more than one definite pro- 
portion. The expression of the law, simply means, that the 
first proportion in which two bodies unite, is in the lowest or 
smallest proportion in which the two constituents are capable 
of uniting with each other, and that the other proportions are 
double, triple, or quadruple, this lowest proportion. 

For example, the several compounds of nitrogen and oxy- 
gen are in the following proportions to each other, viz. : 

Nitrogen. Oxygen. 

Nitrous oxide, consists of 14 parts, and 8 parts. 
Nitric oxide, '' 14 " 16 " 

Hyponitrous acid, " 14 " 24 " 

Nitrous acid, " 14 ** 32 " 

Nitric acid, " 14 " 40 " 

Thus the lowest proportions in which oxygen and nitrogen 
combine, being to each other as the numbers 8 and 14, all the 
other proportions of oxygen are multiples of this first number, 
while the proportion of nitrogen remains the same. The se- 
cond number is the first multiplied by 2 ; the third, the first 
multiplied by 3 ; and so on. These proportions are therefore 
to each other, as the numbers 1, 2, 3, 4, and 5. 

Illustrations of this law can be observed throughout every 
department of chemistry, where the analysis of chemical com- 
pounds are given, and with a single exception, or two, where 
it is most probable the fault is either in the analysis or the 
want of knowledge, the same principle is found to be exactly 
true. One of these exceptions is found in an oxide of man- 
ganese, and will be pointed out hereafter. 

On these discoveries is founded the law, called the law of 
multiple proportions^ a phrase which is often repeated in all 
the late works on Chemistry, and of its general truth, as 
already observed, there can be no doubt. In the above ex- 
ample, all the succeeding proportions of oxygen are multi- 
ples of the first. 



What is the second law of definite proportions 1 What explanations ar« given of thia 
"aw % Suppose the smallest proportions in which nitrogen and oxygen combine are 14 ol 
the first, and eight of tJie last by weight, what then will he the second proportion id 
which oxygen combines with nitrogen 1 Wliat the third, what the fourth, and what the 
fiOhi 



t»ROPORTIONS. 89 

The third law of combination is nearly connected with the 
.ast, though the difference of expression and of meaning will 
be obvious. This law is not less extraordinary than that of 
multiple proportions, and may be understood by the following 
examples given by Dr. Turner. 

Water, we have already seen, is composed of 8 oxygen and 
1 hydrogen: hyposulphurous acid is composed of 8 oxygen 
and 16 sulphur. Now it is a curious fact, that the gas, called 
sulphuretted hydrogen, is constituted of 1 hydrogen and 16 
sulphur ; that is, the quantities of hydrogen and of sulphur 
which combine with the same quantity of oxygen, combine 
with each other. Again, 36 parts of chlorine and 8 of oxygen 
constitute the oxide of chlorine, and with 1 of hydrogen, form 
muriatic acid gas: also 16 parts of sulphur combine with 3b 
of chlorine to form the chloride of sulphur. Hence bodies 
unite in proportional numbers, as in the above instances the 
proportion oi hydrogen is 1, Xhsii oioxyg en S, that of sulphur 
16, and that of chlorine 36. 

But this law not only applies to the elementary parts of 
substances, such as hydrogen, oxygen, chlorine, and sulphur, 
but also to compound bodies : whose combining proportions 
may likewise be expressed by numbers. 

Now the proportions of any compound being expressed by 
the numbers attached to each element of which it is compo- 
sed, the number representing the compounds, is composed of 
the sum of its parts, or elements. Thus water is composed 
of oxygen 8, hydrogen being 1, and its combining proportion 
will therefore be 8+1=0. When one element combines 
with another in several proportions, the number representing 
the single proportion, and those representing the several other 
proportions, are added together to make up the combining 
number of the compound. Thus, sulphuric acid is composed 
of one proportion of sulphur 16, and three proportions of 
oxygen ; and as one proportion of oxygen is 8, so the whole 
number representing the oxygen in this acid is 24; to which 
16 being added, makes the number representing sulphuric 
acid to be 40. 



What is the third law of definite proportions'? Explain this law. Suppose 64 represents 
the metal, and 8 the oxygen, in an oxide of copper, and suppose there is a second oxide, 
what would be the numbers representing the metal and the oxygen? Does this 
law of numbers apply to the elements of bodies only, or to the compounds also % 
When the numbers for the elements of a compound are known, how may the 
number for the compound be found 7 What are the numbers for hydrogen anO 
oxvsen in water! 



90 DEFINITE PROPORTIONS. 

It must be reinembered that the smallest proportion, by 
weight, in which an element is fomid to combine, is the 
fixed number by which that element is always represented. 
Oxygen is invariably represented by 8, because this is the 
smallest proportion in which it is known to combine with 
any other substance. Thus, also, water is composed of oxy- 
gen 8, and hydrogen 1 ; potash of oxygen 8, and the metal, 
potassium, 40. The lowest proportion in which sulphur is 
known to combine with any other substance is 16, and there- 
fore sulphur is always represented by this number. Thus 
sulphuret of lead is com.posed of 1 proportion of sulphur 16, 
and one of lead, whose combinmg number is 104. Its num- 
ber therefore is 16-f-104=120. We have just mentioned 
that the combining number of any compound is represented 
by the sum of its simple, or elementary parts. This will now 
be understood ; for by adding the numbers representing the 
elements in each of the above examples, we shall have those 
by which the compounds are represented. The number for 
water, as already sho^vn, is 9 ; the number for potash is 48, 
viz. 8 oxygen and 40 potassium ; that for sulphuret of lead 
is 120, viz. sulphur 16, and lead 104. 

By remembering the combining weights of the elements 
of any compound, the number representing that compound 
may at once be known. For example, hydrate of 'potash i? 
composed of Avater and potash; water is composed of oxy- 
gen 8, and hydrogen 1=9. Potash is composed of potas- 
sium 40, and oxygen 8=48. These two sums being added, 
viz. 9 + 48=57. Thus the number for hydrate of potash is 
57. Again, the salt called svJphate of pvtash is compounded 
of sulphuric acid and potash. Now to find the number re- 
presenting its combining proportion, we have only to remem- 
ber that sulphuric acid is composed of one proportional of 
sulphur 16, and 3 proportionals of oxygen 24, and that the 
sums of these two numbers are 40. The number for potash. 
as above seen, is 48; therefore the number for sulphate of 
potash, being the sum of these two numbers, is 40+48=88, 



What then is the number for water 1 How does it appear that 40 is the nrimber foi 
milphuric acid 7 Are the numbers for each element and compound invariable ? On what 
circumstance is the numlier for an element founded 7 What is the n'amber for sulphu- 
ret of lead 7 What other number is this number composed of 7 Hydrate of potash is 
composed of water and potash, how will you find the number which represents hydrate 
of potash 7 What is the composition of sulphate of potash 7 How may the number re- 
presenting this compound be found 7 



DEFINITE PROPORTIONS. 91 

It IS unnecessary to adduce further examples, since the in- 
telligent student will be able to understand from the above 
epitome, not only on what kind of facts the laws of definite 
proportions are founded, but will also, it is hoped, be able to 
apply the above principles to the proportional numbers of the 
most common substances to be mentioned hereafter. 

CombinoAion by Volumes. The doctrine of definite pro- 
portions was founded on the suggestions of Mr. Higgins, of 
Glasgow, published in 1789. But it was Mr. Dalton, of Man- 
chester, in England, who established the law^s of chemical 
combinations, and who has the merit, of not only discovering 
almost all that is known in the details of this subject, but also 
of having brought it distinctly before the w^orld. Mr. Dalton 
published his views of the doctrine of definite proportions, in 
1808, soon after w^hich, Gay Lussac, a French chemist, pro- 
ved by a publication in one of the journals, that gases unite 
m simple and definite proportions, and among other instan- 
ces, showed that water is composed precisely of 100 volumes 
of oxygen, and 200 volumes of hydrogen. It was afterw^ards 
shown by the same author, that other gaseous substances, 
which are capable of a chemical union with each other, unite 
in definite proportions, by measure, or volume, and that these 
proportions are in the simple ratio of 1 to 1, 1 to 2, 1 to 3, 
and so on, as above stated. 

These observations have since been confirmed by nume- 
rous experiments, instituted by the first chemists of the age, 
and at present it is as fully established, that the law of defi- 
nite proportions extends to the volumes of gases, as it does to 
their weights and to those of solids. As an illustration of the 
truth of this law, w^e adduce the condensation of hydrogen 
and oxygen by combustion, because these gases are more 
generally known than any others, and because their combi- 
nation is also one of the most familiar examples of definite 
proportions by w^eight. The apparatus for this purpose it is 
unnecessary to describe, it being sufficient for our present 
purpose, to state that the experiment has often been made 
with the most infallible accurac3^ 

The invariable proportions in w^hich oxygen and hydrogen 

Who first suggested the doctrine of definite proportions 1 Vv^ho extended this sub- 
ject, and brought it before the public 7 What is said relative to the union of tho 
gases by volume ? In what ratio do the gases combine by volume? What illu» 
tration is given of the union of the gases by volume 1 What are the proportions in 
which hydrogen and oxygen combine by volume, and what are these proportions by 
weight % 



92 DEFINITE PROPORTIONS. 

combine, are by volume 1 of the first and 2 of the last, and 
by weight 16 of oxygen to 1 of hydrogen. Thus the speci- 
fic gravities of these two gases are to each other as the num- 
bers 1 and 16, that is, a cubic foot of oxygen is just 16 times 
as hea\y as the same bulk of hydrogen. The reason why 
hydrogen is represented by 1, as its combining proportion, by 
weight, while its combining volume is double that of the oxy 
gen, will be seen hereafter. The mode of ascertaining the 
comparative volumes in which these two gases comibine, is to 
measure them carefully, and having introduced them into a 
glass tube, the mixture is inflamed by an electric spark ; and 
in every instance it has been found, that whatever the propor- 
tions of the mixture might be in respect to each other, the ra- 
tio of combination is always the same, and consists of two 
parts of hydrogen, and one of oxygen, by volume. When 
one measure of oxygen is mixed with three of hydrogen, 
there will remain in the vessel one measure of hydrogen un- 
combined and pure, and no continuance of the electricity v\'ill 
in the least change this' proportion ; and so, two measures oi 
oxygen and two of hydrogen, leave one measure of oxygen 
in the same manner. 

When other gases unite merely in consequence of being 
brought into contact, and without com.bustion, the same law 
applies, that is, if the volume of one be greater than its com- 
bining proportion, the excess remains pure and untouched. 

We give a few examples of the proportions in which ga- 
ses unite by volume. 

Volumes. Volumes. 

1 00 muriatic acid gas combine A\^th 1 00 ammoniacal gas, 
iOO oxygen gas *' 200 hydrogen gas, 

100 hydrogen gas " 50 oxygen ^s, 

100 nitrogen gas '* 200 oxygen oas, 

100 chlorine gas " 100 hydrogen gas, 

iOO nitrogen gas '* 300 hydrogen gas. 

Another curious fact concerning the union of the gase^ is, 
that many of them suffer a diminution of bulk, which is also 
in a simple ratio to the volume of the one or both. Thus, when 
3 volumes of hydrogen and 1 of nitrogen combine, they in- 



' WTiat are the relative specific gravities of these two gases 7 What is the mode of a« 
certaming the volumes of these gases ? Suppose one measure of oxygen is mixed wiib 
three of hydrogen, and inflamed, what will become of the third measure of hydrogen? 
Docs the same law apply when two ga.«e3 combine without combustion 1 What illu3 
rations are given of the combiiiation of ga^ea by volume 1 



L-y' 



CHEMICAL EQUIVALENTS, 93 

stantly contract into 2 volumes, or one half their former bulk, 
and form gaseous ammonia. A similar condensation takes 
ace when several of the other gases combine. 

Chemical Equivalents. It was long since proved by Wen- 
zel, a German chemist, that when two neutral salts decom- 
pose each other, the resulting compounds are likewise neu- 
tral. That is, the acid of one will exactly neutralize the alkali 
of the other ; and although two new salts are formed by this 
mutual decomposition, they will both, like the original com- 
pounds, be equally neutral. If one of the salts be in quan- 
tity too large for the combining proportions, then the excess 
of that salt vAW remain undecomposed in the solution, and 
only such a portion of it will be decomposed as is just suffi- 
cient to neutralize the constituents of the other salt. 

Hence, Chemical Equivaleiits are those definite propor- 
tions of one substance, ivhich neutralize definite proportions 
of another suhstaiice. 

The truth of this law may be demonstrated by setting down 
the combining numbers of two salts, and the number repre- 
senting the two new compounds, and then by exchanging the 
numbers representing the combining parts, the numbers for 
each compound will be found to represent the number for the 
new compound, and the combined numbers of the old and 
new compounds will be equal to each other. Thus, the num- 
ber for sulphuric acid is 40, and the combining proportion of 
potash is 48, and therefore the number for sulphate of potash 
is 88. The combining proportion of nitric acid is 54, an-d 
that of baryta 78, and the sum of these two numbers is 132, 
which represents the nitrate of haryta. Now when these 
two salts are mingled together in solution, both are decom- 
posed ; the 54 parts of nitric acid of the nitrate of haryta will 
saturate the 48 parts of potash of the sulphate of potash, ma- 
king a new salt, nitrate of potash, whose combining number 
is 102. At the same time, the 40 parts of sulphuric acid of 
the sulphate of potash, will combine with, and saturate, the 78 
parts of the barjrta of the nitrate of haryta, forming another 
new salt, sulphate of haryta, whose number will therefore 
be 40 added to 78=118. 



What ig meant by chemical equiyalents 7 How may it be proved that when two salta 
decompose each other, the acid of one exactly neutralizes the alkali of the other 7 What 
nmnber represents nitrate of baryta 1 What number represents sulphate of potash! 
When these two salts decompose each other, what are the namea of the new salts formed 
and what is the number for each 7 



94 CHEMICAL ECiUlVALENTS. 

Now it may be observed that the sums of the proportional 
numbers of the old and new compounds are equal, and the 
same, and therefore that there can be no excess in either of 
the alkalies or acids. This may be shown thus : 

Sulphuric acid 40 and potash 48, form sulph. potash, 88 
Nitric acid 54 and baryta 78, form nitrate baryta, 132 

Sum of the old compound, 220 

Sulph. acid 40 and baryta 78, form sulph. of baryta, 1 1 8 
Nitric acid 54 and potash 48, form nitrate of potash, 102 

Sum of the new compound, 220 

The utility of being acquainted with these important laws, 
says Mr. Turner, is almost too manifest to require notice. 
Through their aid, and by remembering the proportional num- 
bers of a few elementary substances, the composition of an 
extensive range of compound bodies may be calculated with 
facility. By knowing that 6 is the combining proportion of 
carbon, and 8 of oxygen, it is easy to recollect the composi- 
tion of carbonic oxide, and carbonic acid ; the first being 
composed of 6 carbon and 8 oxygen, and the second of 6 
carbon and 16 oxygen. By simply remembering, therefore, 
that carbonic oxide is composed of one proportion of carbon, 
and 1 proportion of oxygen, and knowing that carbon is 
represented by 6 and oxygen by 8, we at once arrive at its 
composition. And by recollecting that carbonic acid has 1 
proportion of carbon, and 2 of oxygen, the composition of 
this is also known. It may be remembered that the number 
for potassium is 40, and that Avhen combined with one pro- 
portion of oxygen, 8, it forms potash, 48. Now by remem- 
bering these data, we know without further trouble the com- 
position of the carbonate and bicarbonate of jpotash. The car- 
bonate being composed of one proportion of carbonic acid, 
22, (that is 6 carbon and 16 oxygen,) and one proportion of 
potash, 48, (that is, potassium 40 and 8 oxygen,) is represent 
ed by 70. The bicarbonate is composed of one proportion 



What is the sum of the numbers of the old salts, and what the sum of the numbers 
of the two new salts 7 What is the equivalent number for carbon 7 What is the equi- 
valent number for oxygen 7 Carbonic aci:l is composed of 1 equivalent of carbon, and 2 
equivalents of oxygen now what is the number for carbonic acid 1 Why is the number, 
«r equivalent, of carbonate of potash 70 1 



CHEMICAL EQUIVALENTS. 95 

of potash, 48, and two of carbonic acid, 44, and its number 
is therefore 92. 

Again, having in the memory the numbers representing 
carbonic acid, we can readily apply them to the composition 
of other compounds, with which this acid is united. Thus, 
the number for carbonate of soda, is 54, and we know from 
its name (see Nomenclature,) that it contains only one pro- 
portion of carbonic acid. Now by recollecting the combin- 
mg proportion of sodium, we know, in a moment, the compo- 
sition of the carbonate of soda. The combining number for 
carbonic acid being 22, this substracted from 54, leaves 32, for 
the other combining proportion, and knowing that 24 is the 
number for sodium, and that soda is composed of sodium and 
oxygen, and that the combining number of oxygen is 8, we 
ascertain the composition of the salt in question, viz. sodium 
24, oxygen 8,=32 soda ; carbonic acid 22=54, carbonate of 
soda. 

By the same law of proportions, suppose it is required to 
find the composition of sulphate of soda. The composition 
and number of soda being known, we have only to remember 
that the combining proportion of sulphur is 16, and that sul- 
phuric acid is composed of one proportion of sulphur and 3 of 
oxygen, and the composition of this salt and its number is 
ascertained. Soda 32, sulphur 16; oxygen 3 proportions, 
24, 16=40 added to 32=72. Therefore the number for sul- 
phate of soda is 72, and its composition 32 of soda and 40 of 
sulphuric acid. 

Thus by the application of this law to the combining num- 
bers, or the equivalents of chemical bodies, a table of which 
may be found at the end of this work, the composition of most 
compounds may be readily ascertained. 

Method of ascertaining the proportional nmnhers of compounds. 

The combining numbers of all the elementary bodies, as 
already stated, represent the smallest proportions in which 
they are severally found in union with any other body. But 
it is obvious that all these numbers must have one common 
\init from which they are calculated, otherwise there would 
exist no proportions between them. For this purpose, hydro- 



Why is bi-carbonate of potash represented by 92 ? Why is caibonate of soda represent- 
ed by &4 ? By the same law of proportion, show why the equivalent for sulphate of soda 
iB 72? What are the units or data from which the rombiina? numbers, or equivalej^ts 
are calculated 7 



96 CHEMICAL EQUIVALENTS. 

gen, as uniting in the lowest possible proportion, is employ 
ed. Thus, hydrogen unites with oxygen in one proportion, 
by weight to form water, and the weight of hydrogen being 
1, the weight of oxygen in water is 8, which is also the small 
est proportion in which the latter body is found in union. 

These two elements having an extensive range of affinity 
and therefore being found in combination with a great variety 
of other substances, are made the data, or points of compa- 
rison from which all the other numbers are calculated. 

Afterwards, other compounds were examined which con- 
tained the smallest proportions of these elements united to 
other substances. Among these it was found that the gas 
called carbonic oxide, contained the smallest combining pro- 
portion of carbon, united with the smallest proportion of oxy- 
gen, these proportions being as 6 to 8. And also, that the 
gas called sulphuretted hydrogen, contained the smallest pro 
portion of hydrogen united to the smallest of sulphur, these 
proportions being 1 of hydrogen and 16 of sulphur. 

Thus^ the numbers for carbon and sulphur were found to 
be 6 for the former and 16 for the latter, the numbers for 
hydrogen and oxygen being 1 and 8. 

On examination of the different oxides of iron, it was found 
that the least proportion with which that metal combined 
with oxygen, was that of 28 of the former, and 8 of the latter. 
The number for iron is therefore 28, and that of this oxide 
of iron 32. 

In this manner the proportional numbers of each compound 
has been ascertained, and from these, tables of chemical equi 
valents have been constructed. 

Wollaston^s scale of Chemical Equivalents. 

Dr. Ure says, that this scale of chemical equivalents has 
contributed more to facilitate the general study and practice 
of chemistry than any other invention of man. The descrip- 
tion of this instrument was published by the inventor in 1814. 
It consists of a piece of mahogany board two or three inches 
wide, and of a length proportionate to the extent of the scale 
it contains, or of the size of the type in which it is printed. 
Running through the middle of the board there is a sliding 

Having the numbers for hydrogen and oxygen as data, how are the numbers for other 
bodies found? What are the equivalent numbers for carbon and sulphur? Explain . 
Jiow the number for iron was found. Descril>c the construction of Wollaston's scale or 
chemical equivalents? 



CHEMICAL EQUIVALENTS. 97 

rule, containing the proportionate numbers of all the most 
common chemical compounds, and on each side of the rule 
are printed the names of the compounds corresponding with 
these numbers. The divisions of this scale are laid out logo- 
metrically, after the manner of the common Gunter's scale, 
and consequently the ratios between the numbers are found, 
by the juxtaposition of the several lines, on the sliding and 
fixed parts, with the greatest accuracy. 

The arrangement of this instrument is such, that the weigh 
of any ingredient in a compound, or its definite proportion, ana 
also the equivalents of the acids and alkalies, may be at once 
seen by merely moving the sliding part. 

On this scale, instead of taking hydrogen for unity, Dr. 
Wollaston has taken oxygen, which he calls 1 ; but if we 
slide down the middle rule so that 10 on it stands opposite 
to 10 hydrogen on the left hand, then every thing on the 
scale will be in accordance with Sir H. Davy's system of 
proportions, taking hydrogen for unity, and also in accord- 
ance with the theory of definite gaseous combination, by 
volume. 

The principle on which this instrument works, may be 
learned in a few minutes ; and after a little practice, it be- 
comes one of the most efficient and beautiful of labor-saving 
machines, to both the practical and theoretical chemist. 

Nothing but actual practice with the instrument, will con 
vey to the mind of the learner a knowledge of its practical 
usefulness ; we will however give an example, by Vv'hich the 
principle of its construction may perhaps be comprehended. 

We have already stated, that on this scale oxygen is the 
unit from which all the other proportions are calculated, and 
that this element is marked 10. When therefore, 10 on the 
sliding rule is against this number, the weights of the other 
bodies are in due proportion to this number. Thus carbonic 
acid being 27.54, and lime 35.46, carbonate of lime being 
the sum of these numbers, is placed at 62. Then if the sli- 
ding rule be drawn upwards, so that the number 100, on it, 
corresponds with carbonate of lime, the other numbers will 
correspond with carbonic acid and lime, and will show the 
proportions in which these ingredients unite to form 100 



Wliat principle does Dr. Wollaston call unity, and what ia its number on the scale oi 
chemical equivalents 1 On what evidence is the truth of the doctrine of definite proper 
jons founded 1 

9 



98 ATOMS. 

parts of carbonate of lime. Thus, the number 56 corres 
ponds with lime, while 44 corresponds with carbonic acid, 
these two numbers making 100. 

Theory of Atoms. That chemical bodies unite in definite 
proportions, by weight, and also by volume, and that where 
one body unites with another in more than one proportion, 
the second is a multiple of the first, are facts resting on the 
evidence of experiment alone. These facts, in themselves 
so wonderful, and in their relation to science so important 
excited the inquiry and speculations of many philosophic 
minds, as to their cause. Among these inquirers, Mr. Dal 
ton, of Manchester, seems to have been the most successful, 
having proposed a theory which accounts, wdth few, if any 
exceptions, for all the phenomena observed, and which 
therefore explains satisfactorily, the reasons why bodies com 
bine in such proportions. As the basis of this theory, Mr 
Dalton assumes that the union of bodies in their smallest pro 
portions, always takes place between the atoms of which they 
are composed ; that is, one atom of one body combines with 
one atom of the other body. Thus, water is formed by the 
combination of one atom or particle of oxygen combined 
with one particle or atom of hydrogen. This theory sup- 
poses also that the ultimate atoms of matter are indivisible ; 
that they are always of the same shape and size in the same 
body, and that their weights are different in the different 
bodies. Thus, the weight of an atom of oxygen is 8 times 
that of an atom of hydrogen, these being the proportions 
in which these gases form water. But when bodies unite in 
several proportions, then it is 2 or 3 atoms of one, to one 
atom of the other. Thus, sulphurous acid is composed of 
2 atoms of oxygen united to 1 atom of sulphur, and sul- 
phuric acid is composed of 1 atom of sulphur and 3 atoms 
of oxygen, these being the relative weights of their elements. 
But as it is found that the lowest proportion in which sul- 
phur unites with any other body, is in the proportion of 1 6 by 



What is said of Mr. Dalton's theory of atoms 1 What does Mr. Dalton assume 
as the basis of his theory of atoms 1 On this theory what is water composed of 1 
What does this theory suppose, in respect to the divisibility, shape, and weight, of the 
atoms of bodies '? Why is an atom of oxygen supposed to l)e eight times as heavy 
as one of hydrogen 1 Why is an atom of sulphur supposed to be twice as heavy as 
one of oxygen 1 Why is it supposed that sulphurous acid contains 1 »tom of sulphiu: 
united to two atoms of oxygen ? That sulphuric acid is composed of 1 atom of sulphur 
and 3 atoms of oxygen 7 Why is the equivalent number of oxygen 8 1 Why is thai 
Tor sulphur 16 1 



ATOMS. 99 

weight, hydrogen being 1, so it is assumed that a particle of sul 
phur is sixteen times as heavy as one of hydrogen, and twice 
as heavy as one of oxygen. And as in sulphurous acid the 
weight 01 oxygen is found to be exactly double that in water, 
it is reasonable to suppose that sulphurous acid consists of 1 
atom of sulphur united to 2 atoms of oxygen, and for the 
same reason, since sulphuric acid contains three times 
the weight of oxygen that water does, that this acid is com- 
posed of 1 atom of sulphur and 3 atoms of oxygen. 

All this, whether true or false, explains in the most satisfac- 
tory manner, why bodies combine with each other in definite 
proportions, and why these proportions are expressed by the 
numbers attached to each. Thus, hydrogen is unity, or the 
prime equivalent, and is expressed by 1, because by weight 
this gas is found to form water by uniting with 8 parts of oxy- 
gen. Oxygen is expressed by 8, because its proportion in 
water weighs eight time as much as the hydrogen. The 
number for sulphur is 16, because this is the smallest propor- 
tion in which it unites w^th any substance, and the number 
for the oxygen in sulphurous acid is 16, because in this acid 
the sulphur and oxygen are of equal weights, and therefore 
lust twice the weight of the oxygen in water ; and the num- 
ber for the oxygen in isulphuric acid is 24, because its w^eighl 
is three times that in water. 

Now by supposing that one atom of oxygen is 8 times as 
heavy as one of hydrogen, and that an atom of sulphur is 
twice as heavy as one of oxygen, or 16, times as heavy as 
one of hydrogen, the whole mystery of the law of definite 
proportions is reduced to simple arithmetical calculation, for 
the proportional numbers are in fact nothmg more than the 
relative weights of the atoms of which the several bodies are 
composed. 

In respect to the truth or falsity of this theory, it is obvi- 
ously without the bounds of demonstration, for w^e never can 
ascertain whether the proportions on which it is founded are 
the smallest in which bodies combine, nor whether, if so, they 
combine atom to atom, as is supposed. But whether it be 
true or false, it does not in the least affect the truth of the 
law of definite proportions, which, as already stated, is found- 
ed on experiment alone, and is therefore purely an expression 

Why is the number of oxygen in sulphuric acid 24 7 What is said of the proportionate 
ntimbers in relation to the weights of the atoms of bodies 1 Wliat is said in respect to 
the truth of this theory 1 



100 



CHEMICAL APPARATUS. 



of facts. The atomic theory, however, must always be con- 
sidered an elegant and probable hypothesis, and while it dis- 
plays uncommon ingenuity, and great chemical research, has 
the advantage of agreeing, in general, perfectly with the facts 
obtained by analysis. 

Chemical Apparatus. 
Before proceeding to treat of ponderable bodies, and the 

description of particular agents, it is proposed to describe 

some of the most common, and necessary utensils, used in the 

manipulations of chemistry. 

Fig. 29. 

^^,^-— ^ A crucible, Fig. 29, is a deep conical cup, of a tri- 

L__^^_^ angular shape at the top, and round at the bottom. 

\ / Crucibles are made of this shape for the conve- 

\ / nience of pouring out their fluid contents at either an- 

\ / gle. Theyaremadeofclay and sand baked hard, and 

\ — I will withstand very high degrees of heat without 

melting, but are liable, to crack when suddenly cooled. They 

are chiefly manufactured at Hesse, in Germany, and hence 

are called Hessian crucibles. 

A melting pot, Fig. 30. These pots are made of 
various sizes and materials. Those used in glass 
houses are made of clay, and are of large size. 
Chemists employ those made of silver or platina, 
as well as of black lead, but of small dimensions. 
Metallic crucibles are used for particular purposes, 
when the substance to be experimented on would 
destroy the common crucible, in consequence of its 
corrosive quality. 

A matrass. Fig. 31, is a glass vessel, in the shape 

I of an egg, with a long neck. It is employed in ef- 

j \ fecting the solution of such substances as require 

/ \ heat, and long continued digestion, for that purpose. 

/ \ When used, they are commonly placed in a sand 

( J bath, that is, in sand moderately heated. 

Whether it is true or false, does it in the least affect the truth of the doctrine of de- 
finite and multiple proportions 7 What is a crucible, and for what purpose is it v^ 7 
Of what are crucibles made 1 How do melting pots differ from crucibles 7 Of what «aib 
ctances are melting pots made 7 01 what are matrasses made 7 For what purpose t^ 
these \re3sel3 used 7 




CHEMICAL APPARATUS. 



101 



Fig. 32. 




A retort and receiver is repre 
sented at Fig. 32. Retorts, a, 
are Qgg shaped vessels, with 
the neck turned on one side. 
These vessels are of various 
capacities, from a gill to a bar- 
rel, or more. They are made of glass, metal, or earthen 
ware, but most commonly of glass. No vessel is so much 
used in experimental chemistry as the retort. In the process 
of distillation, in collecting the gases, in concentrating the 
acids, and in a great variety of other operations, this vessel 
IS universally employed. 

The receiver, b, is a necessary appendage to the retort, and 
is destined to receive whatever comes over from it, during 
the process of distillation. For common purposes, these ves- 
sels are made of glass, but in the manufacture of various 
articles they are made of wood or metal. 

Fig. 33. Fig. 33, represents a tubulated 

retort. It differs from the plain 
retort, figured above, in having a 
■^tubulure, or opening, as seen in 
the figure, to which is fitted a glass 
ground stopper. This opening 
saves the trouble of detaching the 
retort from the receiver when any 
additions are to be made to its contents, after they are con- 
nected, as in Fig. 32. It is also necessary for the introduc- 
tion of a safety tube, a part of this apparatus, absolutely 
necessary in some processes, and which will be described in 




another place. 
Fig. 34. 




The alembic, Fig. 34, is used fcr the di.=?til- 
lation or sublimation of solid, volatile substan- 
ces. It consists of two parts, the head a, 
which is ground on, so as to be perfectly 
tight, and the body Z>, which is set into a sand 
bath, when in use. The product of sublima- 
tion rises into the head, where it is condens- 
ed, and then runs down the spout into a re- 
ceiver. 



What is a retort ? How large are retorts 1 Of what are retorts made 1 WTiat are th« 
uses of retorts ? What is a receiver, and what is its use 1 Of what are receivers made 1 
How does a tubulated, differ from a plain retort 1 What is the use of the tubulure, or 
opening, in this retort 7 What is an alembic 1 What is the use of the alembic 1 

9* 




.02 CHEMICAL APPARATUS. 

Fig. 35. Evaporating dish, Fig. 35. Every chemi 

=^^^ cal apparatus must have among its utensib 
^^^Q shallow dishes for evaporating fluids. The 

^ best are made of Wedgewood's ware, and comf 

^^ packed in nests containing several sizes each 
The heat is applied by means of heated sand or ashes, and 
these vessels are used to evaporate solutions of salts, in order 
to obtain crystals, and for various other purposes. 

Fig. 36. Fig. 36, ?i Florence flask, iuTm^YieA. with a 

tube, to be used instead of a retort. Students 

will save considerable expense, by employing 

these flasks in the room of retorts. The 

cork is pierced with a burning iron, and 

through the aperture is passed a tube of glass 

or lead, bent as in the figure. In obtaining 

oxygen, by means of oxide of manganese and 

sulphuric acid, and for many other purposes, 

this arrangement will serve instead of the best retort, while, 

if broken, the expense is only a few cents. 

Fig. 37. The common blow pipe, Fig. 37, is a little instru- 

R ment by means of which the most violent heat of a 

furnace may be produced. It is a pipe of brass, 

about the third of an inch in diameter at the largest 

end, and thence tapering, gradually, to a point, and 

bent, as in the figure. 

To use it, place the curved end in the flame of a 
lamp, or candle, and apply the lips to the other end, 
then blow gently and steadily, giving the jet of flame 
a horizontal direction. To keep up a constant stream 
of air for a length of time, the inspiration must be 
ma de by the nostrils, while the cheeks are used as 
bellows. The art of doing this is soon learned by practice. 
The small fragments of ore, or other substance, on which the 
flame is thrown, must be laid on a piece of charcoal, which 
is held by small foreceps. When a very intense heat is re- 
quired, and the fragment is so light as to be blown away by 
the air, it may be confined by making a small cavity in the 
charcoal support, into which the substance is put, and anothei 
piece of charcoal is placed partly over this. 



Of how many parts does the alembic consist 1 For what purposes are evaponnion 
dishes employ-ed 7 What does Fig. 36 represent? What are the advantages of iisin< 
Florence flasks instead of retorts ? What is the common Wow pipe 7 What is the tt»« 
of this instrument 1 Describe the mode of using it. 



1 



CHEMICAL APPARATUS. 



103 



Fig. 38. 



^ 



Gah7)Js Blowpipe, Fig. 38, is a much rilore con- 
venient form than the common one ahove descri- 
bed. In the common form, the flame is sometimes 
nearly extinguished, and the process stopped, by 
the condensed moisture from the breath. In 
Gahn's instrument this is prevented by the cham- 
ber a, which retains the condensed moisture, and 
which may be taken off from the main pipe for its 
removal. The tip of the small pipe through 
w^hich the air passes to the flame, fits to a socket, 
so that those of different sized orifices can be used. 
The dropping ticbe, Fig. 39, is a small glass 
tube, blown into a ball in the middle, and ending 
with a fine orifice at the lower end. It is filled by 
dipping the small end into the fluid, and exhaust- 
ing the air by sucking at the upper end with the 
mouth. The thumb is then placed on the upper 
end, which keeps the liquid from running out. On 
Hg. 39. raising the thumb, the contents will descend in drops, 
but is instantly restrained on replacing it. 

This little instrument is highly useful for various 
purposes, and particularly when it is required to intro- 
duce one fluid under another, as w^ater under alcohol, 
or sulphuric acid under water. 

The simple arrangement. Fig. 40, is designed to col- 
lect and retain for the purpose of temporary examina- 
tion, such gases as are lighter than the atmosphere, 
40. and at the same time are absorbable by water. 
These gases, for more thorough examination, re- 
quire the aid of a mercurial bath, but most of their 
properties may be examined by the apparatus re- 
presented by the figure. 

The flask a, is to contain the materials for extri- 
cating the gas, and into the mouth of this, there is 
inserted a tube a foot or more long. The tall bell 
glass b, or a large tube closed at the upper end, is 
inverted over this tube, as seen in the figure. 

As an example of the use of this apparatus, sup- 
pose we desire to make some experiments on am- 
monia, a gas which is rapidly absorbed by water 
and specifically lighter than atmospheric air. The 
materials for separating this gas are muriate of am 




How does Gahn's blowpipe differ from the cor^^saon one 1 What are the peculiar ftd 



104 



CHEMICAL APPARATUS. 



monia, called also sal ammoniac, and slacked quick-lime. 
These being separately reduced to powder, equal parts are 
then mixed, and introduced into the flask a, and the tube put 
into its plaze. On application of a gentle heat, the gas wilj 
be set free in consequence of the combination which takes 
place between the lime and the muriatic acid of the muriate of 
ammonia. The ammonia is thus set at liberty, and being 
lighter than the air, ascends and gradually displaces the air 
from the vessel h, and takes its place. This experiment affords 
nn instance of the chemical action of two solids on each other. 
Fig. 41. Fig. 41 is designed as a 

simple illustration of a 
gas apparatus. The me- 
thod of making experi- 
ments with the perma- 
nently elastic fluids, such 
as common air, and the 
gases, and of transferring 
them from one vessel to 
another, though sufficient- 
ly simple, requires some directions for the beginner. The 
gases are none of them sufficiently dense, to be retained in 
vessels open to the air for any considerable time; and some 
of them being lighter than the atmosphere, instantly ascend, 
and are lost, when the vessels containing them are opened. 
All the gases, therefore, when open to the air, mix with it more 
or less rapidly, according to their densities, and thus escape 
us entirely, being diffused in the atmosphere. Hence, to re- 
tain a gas in a state of purity, it must be kept from contact 
with the atmosphere, and hence also the necessity of flrst fill- 
ing the vessel with a fluid instead of air, before the gas is in- 
troduced, and of transferring it under a fluid from one vessel 
to another. 

The figure represents a wooden vessel or tub, a, with a 
shelf k, k, fixed a few inches from the brim. When the ap- 
paratus is to be used, the tub is to be filled with water, 




vantages of this blowpipe 7 Describe the construction of Gahn's bloTvpipe. What is the 
Bhape of the dropping tube? What is the use of iliis instrument 7 Describe the manner 
of using the dropping tube. For what purposes is the dropping tube useful 1 What is 
the use of the apparatus represented by Fig. 40 ? Describe Fig. 40, and explain an ex- 
ample of its use. IIow may ammonia be obtained and examined by means of this appa 
ratus 7 What is represented by Fig. 41 7 Why cannot the gas be poured from one ves 
eel U) another, and be retained in an open vessel like water 7 



CHEM.CAL APPARATUS. 105 

80 as to rise a few inches above the shelf. Now when a 
glass jar, or any other vessel, open only at one end, is filled 
with water, by being plunged into the fluid, it will retain its 
contents when raised above the fluid, provided its mouth be 
kept under it ; for the water is sustained in the vessel by the 
pressure of the atmosphere, on the same principle that the 
mercury is sustained m the barometer tube. (See Barometer 
ill Natural Philosophy.) The vessels Z>, g, f, represent jars 
filled with water, and inverted on the shelf, their necks pass- 
ing through an aperture in it, so as to preserve their uprigh; 
positions. The vessels e, c, and i, are retorts, with their 
necks inserted into the mouths of the inverted jars. 

Now when common air, or any gas, is introduced into the 
mouth of a vessel so inverted, the air will rise to the upper 
part of the vessel, and will displace the water, and occupy its 
place. If a tumbler, or cup, in the state which we usually 
call empty, but which is really full of air, be plunged into 
water with its mouth downwards, very little water vdll enter 
it, because the admission of the fluid is opposed by the in- 
cluded air ; but if the mouth of the vessel be turned upwards, 
it immediately fills with water, while the air is displaced, and 
rises to the surface of the fluid in one or more bubbles. 
Suppose this is done under the mouth of a jar filled with wa- 
ter, the air will ascend as before, but instead of escaping, it 
will be detained in the upper part of the jar. In this man- 
ner, therefore, air may be transferred from one vessel into 
another, by an inverted pouring, and the first portions, in- 
stead of occupying the bottom of the vessels, like water, as- 
cend to the top, the air, instead of running from a higher 
to a lower vessel, rising from the lower to the higher one. 
This is owing to the pressure of the water on the air, or to 
the lightness of air when compared with water. For the 
same reason, lead being lighter than quicksilver, if a bullet 
of the former be sunk in a vessel of the latter, it will rise to 
the surface. On this principle balloons ascend ; the hydrogen 
with which they are charged being 13 times lighter than the 



Explain the reason why a vessel filled with water may be raised above the fluid, pro- 
rided its mouth be kept under it. WTien a tumbler is forced into the water with its 
mouth downwards, why does not the fluid rise in it? Wlien air is introduced imder a 
vessel, inverted and filled with water, why does it rise to the highesi part of the ^ 
flow does the rise oi a balloon illustrate this principle 1 




106 CHEMICAL APPARATUS. 

atmosphere, the former is forced upwards by the pressure of 
the latter. "" 

A hell glass receiver, Fig. 42, is employed in 
making experiments on air, or the gases. It is 
a glass vessel, of the shape represented in the 
figure, and of various sizes, from the capacity of 
a pint to that of several gallons. The knob at 
the upper part, is the handle by which it is 
moved. It is used for the temporary confine- 
ment of elastic fluids, on which experiments are 
to be made. Large tumblers are good substi- 
tutes for bell glasses. 

A lamp furnace, Fig. 43, is one of 
the most indispensable articles in a 
chemical apparatus. It consists of a 
rod of brass, or iron, about half an 
inch in diameter, and three or four 
feet lomr, screwed to a foot of the 
same metal, or to a heavy piece oi 
wood. On this rod, slide three or 
four metallic sockets, into w^hich are 
' screwed straight arms terminated 
with brass or iron rings of different 
diameters. The screws cut on the 
ends of the arms where they enter 
the sockets are all of the same size, 
so that the rings may be changed 
from one socket to another, as con- 
venience requires. These rings are 
for the support of retorts, receivers, 
evaporating dishes, &c., as repre 
i:ented in the figure, and may be 
moved up, or down, or turned aside, 
and then fixed in their places, by 
means of thumb screws passing through the sockets and act- 
ing on the rod. The lamp by which the heat is given for dis- 
tillation, or other purposes, is also fixed with a thumb screw, 
so that the heat can be regulated by moving it up or down. 
Specific Gravity. The specific gravity of a body is its^e 




What does Fig. 42 represent 7 What is the use of the bell glass receiver ? Describs 
tlie lamp furnace, Fig. 43. What are the uses of the rings on the ends of the arms! 
What are the uses of the thumb screws with which the sockets emd lamp are furnished 
What is the specific gravity of a body 7 



CHEMICAL APPARATUS. 107 

ialive weight when compared with the same bulk of another 
body. For solids and liquids, water is the substance to which 
the weight of other bodies are compared ; and for elastic 
fluids, the atmosphere is the standard of comparison. 

When a body weighs twice as much as the same bulk of 
water, it is said to have the specific gravity of 2 ; and if it 
weighs three, four, or five times as much as the same bulk of 
water, it has the specific gravity of 3, 4, or 5. Water, there- 
fore, is the unit, or standard of comparison, and has in this 
respect the specific gravity of 1. 

When a body is weighed in water, its weight will be di- 
minished by exactly the weight of a quantity of water equal 
to its own bulk, and thus the difference between its weight 
ui air and in water being known, its specific gravity is readily 
found. 
Fz^\M. TjjQ i^ciQst simple mode of taking the specific gra 
f^ vity of a solid, is by means of Nicholson^ s Portable 
Balance, represented by Fig. 44. The body is a hol- 
low cylinder of tinned iron, terminated at each end 
by a cone. From the vertex of the upper cone rises 
the small stem a, of copper or brass, bearing a small 
||p U tin cup. This cup slips on, and may be removed 
jj when the instrument is not in use. From the point of 
i the lower cone is suspended the tin cup e, at the bot- 
torn of which is attached a cone of lead so heavy as 
to sink the whole instrument in water nearly to the 
base of the upper cone. Before this balance is used, 
it is placed in a vessel of water, and the upper cup 
loaded with weights until it sinks so far that a mark 
on the stem at a, coincides exactly with the surface of 
the water. The weights so added are called the balance 
weights, and their amount may be marked on the cup as a 
given quantity for future use : suppose this is 900 grains. 

The specific gravity of a solid may then be taken as fol- 
lows. First place it in the upper cup, and add weights until 
the mark on the stem coincides with the water ; suppose this 



With what substance are soHfJs and liquids compared to find their specific gravities % 
What is the standaid of comparison for elastic fluids? Suppose a body weighs twice as 
much as the same bulk of water, what is its specific gravity 1 V^at does Fig. 44 repre- 
R.'nt 1 Describe this balance. What preparation is necessary before the balance is used* 
What are the balance weights? After the balance weight is known, how will you pro 
ceed to find the specific gravity of a body ? 



108 CHEMICAL APPARATUS. 

to be 400 grains ; subtract this from the balance weight, and 
we have 500 grains for its weight in air. Then remove the 
•subject of experiment to the lower cup, and the stem will 
rise above the mark, because it weighs less in water than in 
air ; weights must therefore be placed in the upper cup until 
the mark again coincides with the surface of the water : sup 
pose this to be 100 grains, Avhich wdll be exactly the v/eight 
of the water displaced by the mineral or other solid. The 
specific gravity is now found by a very simple rule, namely, 
Divide the weight in air by the loss in loater, and the quotient 
will be the specific gravity. 

In the present instance, we have 500 grains for the weight 
m air, and 100 for the loss in water ; therefore 100 : : 500=- 
5, the specific gravity. 

The most simple method of taking the specific gravity of 
liquids, is by means of a graduated bottle holding 1000 grains 
of water, which is taken as the unit or standard for other 
liquids. 

Fig. 45. Take a small bottle with a long narrow neck, as 
p represented by Fig. 45, and having weighed it accu- 
rately, introduce into it exactly 1000 grains of pure 
water, and mark the level of the water with a file od 
the neck of the bottle. The bottle thus prepared wil) 
serve to ascertain the specific gravity of any fluid, for 

since water is the standard by which the comparativ^e 
weights of all other fluids are known, the same bulk 
of an}^ other fluid, weighed at the same temperature, 
will be its specific gravity. 

Thus, suppose that when the bottle is filled with sulphu- 
ric acid up to the mark at which the water weighed 1000 
grains, it should be found to weigh 1800 grains ; then the 
specific gravity of the acid would be 1800, water being 
1 000. If filled to the same mark with alcohol it might w^eigh 
800 grains. The specific gravity of alcohol would therefore 
be 800, water being 1000. But as it is understood that 
water is the standard of comparison, the specific gravities of 
bodies are expressed merely by the numbers signifying 
their relation to this standard. Thus the specific gravity of 

After finding the weight of a body in air, and its weight in water, what is the 
rule for finding its specific gravity 7 What are the most simple means of finding the 
i^ecific gravity of a hquid? How does a bottle filled with 1000 grains of water, become 
the standard for other liquids 1 Suppose a given bulk of water weighs 1000 grains, and 
the same bulk of another fluid 1600 grains, what would be the specific gravity of the , 
*atter1 



CHEMICAL ATPARATUS. 109 

lead is 1 1, that is, it is 11 times as heavy as water, bulk for 
bulk; while the specific gravity of ether is 750, that is, a 
given bulk of ether will Aveigh 750 grains, ounces, or pounds, 
while the same bulk of water weighs 1000 grains, ounces, or 
pounds. (See spec. grav. in Nat. Philosophy.) 

To determine accurately the specific gravity of the gases, 
is an operation of great delicacy, and requires not only very 
nice apparatus, but much experience. The method by which 
it is done is, however, easily explained, and will be readil 
understood. 

We have already said that atmospheric air is the standard 
of comparison for the gases. In the first place, therefore, it 
is necessary to ascertain the weight of a given volume of air. 
This is done by weighing very accurately, a light glass ves- 
sel furnished with a good stop-cock, when full of air, or in 
its ordinary state. Then having withdrawn the air, by 
means of an air pump, and closed the stop-cock, the vessel 
is again weighed, and the difference will show the weight of 
air which the vessel contained. On making this experiment, 
it is found that 100 cubic inches of air weigh 30.5 grains, and 
hy the same method, the weight of a given portion of any 
elastic fluid may be ascertained. In all these experiments, 
it is understood that the thermometer stands at 60° and the 
barometer at 30°. 

Fig. 46. Suppose, then, that the glass globe Oj, Fig. 46 
is of sufficient capacity to contain 100 cubic 
1^ inches of air weighing 30.5 grains, and it is found 
on filling it with oxygen that the same quantity 
of this gas weighs 34 grains. Then to find the 
specific gravity of the latter gas we say, ''as the 
weight of the air is to that of the oxygen^ so is 
unity, or the specific gravity of the atmosphere 
to the specific gravity of oxygenP Thus, 30.5: 
34:: 1=1.1147. gives 1.1147 for the specific 
gravity of oxygen gas. 

But since it is inconvenient in practice to ex- 
periment on just 100 cubic inches of gas, the 
graduated vessel h, has been invented, to show 
^at once what quantity of gas in cubic inches is 
weighed in the globe a. 

The globe being first exhausted of air, and its 
stop-cock closed, is then connected with the re- 
ceiver h, containing the gas, and both cocks 

IIow is the specific gravity of a gas ascertained 1 

10 




! 


^ 




t 




.20 


. . 




.SO 






-4^ 


4 


. 


r60 


» 




-eo 


\ 




r7^ 


s 




SO 


% 




r-^0 


\ 




-W 


4 

r 









110 NOMENCLATURE 

being opened, the gas passes from the receiver to the globe 
The receiver being open at the bottom, and set over water, 
or mercury, the rise of the fluid will show the quantity of gas 
which passes into the globe, and on weighing the globe both 
before and after connecting it with the receiver, the differ 
ence will show the weight of the air thus transferred. 

Nomenclature. — ^"^ 

The nomenclature of Chemistry, now universally employ- 
ed, was invented by the French chemists about 1784. Be- 
fore that period, the names of chemical substances w^ere en- 
tirely arbitrary, that is, each substance had an independent 
name, the signification of which had nothing to do with its 
composition, or often gave an erroneous idea concerning it. 
Thus, solution of muriate of lime was called liquid shell, and 
afterwards oil of lime. Liquid ammonia was called bont 
spirit, and sulphuric acid Vv^as called oil of vitriol. It is 
true, at that time the substances known to chemists were few 
in number, when compared with the immense list of the 
present day. But even then, their number was such as to 
make it difficult for the memory to retain them, and at th& 
same time to remember their origin or composition, when 
this was known. At present, were the substances mentioned 
in any chemical book merely designated by arbitrary names 
or names inexpressive of their composition, the student would 
necessarily spent more time in learning and remembering 
them, than is now required to obtain a knowledge of the 
whole science of Chemistry. The general diffusion o) 
chemical knowledge, therefore, is in a great measure owing 
to the present nomenclature, — its perfect simplicity, its co- 
piousness of meaning, and the ease with which it is learned 
and retained. 

Each term in this nomenclature designates the composi 
tion of the compound substance to which it is applied ; ana 



What is the weight of 100 cubic inches of common air 1 Suppose it is found that 100 
cubic inches of oxygen gas weighs 34 grains, how is its specific gi-avity found? Explain - 
Fig. 46, and show the design of each vessel, and the manner of using them. When was • 
1]\e chemical nomenclature invented, and by whom? Before this invention, how wera 
chemical substances designated 1 What is said concerning improper names before this 
invention 7 At present, were the substances known to chemists designated only by arbi- 
trary names, what would be the consequence to the learner 1 What effect has this no 
menclature had on the diffusion of chemical knowledge? By this nomenclature what 
do the names of the substances designate? 



NOMENCLATURE. Ill 

as the simple substances are comparatively few, the compo- 
sition of most chemical substances are known only by thevse 
names. 

The names of the acids are derived from those of their 
bases, that is, from the names of the substances to which 
oxygen unites in such proportions as to form acids. Thus, 
sulphur is the base of sulphuric acid, and carbon is the base 
of carbonic acid. Some of these bases unite with several 
proportions of oxygen, and form acids of different degrees 
of strength. These proportions are designated by the differ- 
ent terminations of the name of the acid, the smaller pro- 
portion being signified by ous and the larger by ic. Thus, 
sulphur 02^5 and sulphuric, and niXxous and nitric acids, mean 
that these acids contain single and double proportions of oxy- 
gen. The salts, that is, the compounds which the acids 
form with alkalies, earths, and metallic oxides, also indicate 
by their names the substances they contain. Thus, the salts 
ending in ite consist of a base, united to an acid ending in 
ous ; and a salt ending in ate contains an acid ending in ic 
Sulphide and phosphide of potash are formed of potash and 
sulphuro2^5 and phosphorous acids, while sulph(^i^e and phos- 
phate of potash denote compounds of sulphuric and phos- 
phoric acids, united to the same base. The names of all 
the salts, of w^hich there are nearly 2000, denote their com- 
position in the same manner, and thus Vv^e know the ingredi- 
ents of their compositions by merely seeing their names. 
The termination uret denotes the union of simple non-metal- 
lic bodies with a metal, a metallic oxide, or with each other. 
Thus, snl^huret and carbz^-rc^ of iron, indicate a combination 
between sulphur or carbon with iron. As oxygen combines 
with several of the metals in different proportions, but not al- 
ways sufficient in quantity to form acids, the compounds so 
formed, though derived from the same metal, differ from each 
other. These compounds are called oxides, and are distin- 
guished from each other by the Greek derivatives, ^rot, deut, 



From what are the names of the acids derived 1 What is the base of sulphuric acid 1 
What is the base of carbonic acid? By what termination in the word is a weak acid de- 
signated 1 By what termination is the strong acid indicated 1 WTiat are the compounds 
safled which the acids form with different bases 1 If an acid ends in ous, what is the 
termination of the salt of which it composes a part? If the acid ends in ic, how doea 
the salt end 7 How will you know the composition of a salt by merely hearing its name 1 
WTiat does the termination uret denote 1 What is the composition of a caxhuret of 
•^Iphur 1 Wliat are oxides ''. 



.12 NOMENCLATURE. 

frit, and per. Pr(?/oxide signifies the first degree of oxida 
tion; c?e2^^oxide, the second ; /r^/oxide, the third; and _peroxide. 
the highest. In some of the salts, it was formerly supposed 
that the acid prevailed, or that more acid was present thai\ 
necessary to saturate the alkali, and in others that the aJkah 
prevailed. The first of these were called supersdli^, and 
the second 52^Z>salts, v/hile those in which the acid and alkali 
•were in due proportion, were called neutral salts. These 
names are now regulated by the atomic constitution of the 
salt. If it is a compound of one atom of acid and one of al- 
kali, the generic name is employed, as carbonate of potash. 
But if two or more atoms of the acid be combined with the 
same base, a numeral is prefixed to indicate its composition 
in this respect. Thus, when the acid is in two proportions, 
or there are two atoms of acid to one of potash, it is called 
Z>i-carbonate of potash. The three saUs of oxalic acid and 
potash are called the oxalate, Z>i7iOxalate, and ^'^a^roxalate of 
potash, the first consisting of one atom of each, the second 
of two atoms of acid to one of potash, and the third of four 
atoms of acid to one of potash. 



PART II. 

PONDERABLE BODIES. 



Explanations. A ponderable body, is one which has ap 
preciable weight. 

A simple body, is one which has not been decomposed 
These are also called elements, or elementary bodies. 

It is possible that all the substances now called elementary^ 
may still be in reality compounds, for our knowledge on this 
subject is entirely negative, that is, all bodies which the art 
of chemistry has been unable to separate into parts, or to de- 
compose, are called simple, in order to distinguish them from 



By what terms are the different oxides denoted 1 What is a dcM^oxide ? What is a 
tn'foxide 7 What is a peroxide 7 Wliat is said of swpersalts and suftsalts 7 WTiat are 
carbonate and Wcarbonate of potash 7 What is a ponderable body 7 What is a simple 
body 7 WTiat is the difference between a simple and an elementary body 7 When do 
eliemiata call a body simple 7 



PONDERABLE BODIES. 113 

Known compounds. Before the refinemerjts of chemical 
analysis were known, it was . believed that nature afforded 
only four elements, viz. fire, air, earth, and water. Analysis 
has however shown, that fire, or heat, is the result of chemi- 
cal union ; that air is a compound of nitrogen and oxygen ; 
that there are many earths, and that water is composed of 
hydrogen and oxygen. 

The number of simple bodies now enumerated amount to 
about fifty, or perhaps iifty-two. They consist of about 40 
metals, three, or perhaps four supporters of combustion, viz. 
oxygen, chlorine, and iodine, and probably also bromine, and 
seven non-metallic combustibles, viz. phosphorus, carbon, 
hydrogen, sulphur, boron, selenium, and nitrogen. 

Only a few years since, potash, soda, and several other 
substances, now found to be compounds, were supposed to be 
elementary bodies ; and it is highly probable, that many sub- 
stances, now arranged as simple, will soon be found to be 
compounds. 

Before proceeding to describe the properties of the gases, 
it might be thought necessaryto detail more particularly than 
has been done, the modes of confining and transferring them 
from one vessel to another. But it is thought that such di- 
rections are better understood by the student, and much more 
readily follow^ed when given in connexion with the particu- 
lar subjects or cases, to which they immediately apply. The 
method, for instance, of transferring the nitrous oxide from 
the retort to the gasometer, and from the gasometer to the 
gas bag, wdll be best understood if given in connexion with 
an account of the properties of the gas, or immediately after 
it. The same, it is thought, may be said of confining and 
transferring the other gases. As several different methods 
are required, depending on the nature of the gas, its absorp- 
tion by water, its specific gravity, and other properties, these 
different modes can be best explained and understood in im- 
mediate connexion with the description of the peculiar pro- 
perties of each gas. 

As the doctrine of definite proportions is not only highly 
interesting as a subject of philosophy, but is also intimately 
connected with chemistry, both as a science, and a practical 



How many elements were formerly supposed to exist ? What is said concerning 
fire, air, earth, and water 7 How many elements are now supposed to exist, and what 
are they 7 What is said of the probability that some bodies now arranged as elements 
will be found to be compounds T 

10* 



il4 PONDERABLE BODIES. 

art, we shall attach to the name of each substant ; at the head 
of sections, its equivalent number, so that the reader may al 
once observe its combining proportion. And it is earnestly 
recommended to the pupil, that he should not only regard 
this subject as one of great importance in a 5:cientific relation, 
but also, when viewed in a different light, as one that tends 
directly to impress the mind with the most serious conviction, 
that nothing in nature has been left to chance, but that the 
Almighty Creator has left a witness of himselt even m the 
proportions, and arrangement of the atoms of matter. No- ' 
thing, perhaps, even the sublimest works of nature, are more 
calculated to elicit the wonder and astonishment of a reflect- 
ing mind, than the fact that substances combine with each 
other in exact, and definite quantities, and that these quanti- 
ties or proportions, are the same in relation to the same sub- 
stance throughout the world, and have been so ever since the 
creation. This discovery may be considered as anew proof, 
directed expressly to the present age, that the most minute j 
works of what we call nature, do indeed bear the most indu* j 
bitable marks of divine agency and design. 

But while the discovery itself is an evidence of the profound 
philosophy of the present age, the developement of its prin- 
ciples, by the constant accession of new ideas, is calculated 
rather to humble the pride of human knowledge, by as con- 
stant a conviction, that after all our acquirements, we know 
comparatively nothing of the laws and operations of nature. 
The very fact, that the laws of proportions, now comparatively 
just known to man, have existed ever since the creation of 1 
matter, and have been in perpetual exercise all over the uni- 
verse, without a suspicion of their existence, is of itself a suf- 
ficient proof of the almost entire ignorance of man even of the \ 
phenomena of nature, and a still stronger proof of his igno- 
rance of her laws. And if facts, in themselves so simple, yet 
so wonderful, and when once known, so obvious, have esca- 
ped the observation of man for thousands of years, is it not 



What is said of the doctrine of definite proportions, in relation to pliilosophy and che- 
mistry 1 In what other respects is this subject recommended to the particular attention 
of the pupil 1 What is said of divine agency and design in the minute works of nature 1 
After all human acquirements, how much do we know of the laws and operations of na- 
ture 1 Wliat is proved by the fact, that the law of definite proportions, though existing 
ever since the creation of matter, have, until la^tely, remained unknown'? What is said 
of the probability that wonderful phenomena ai-e constantly going on before our cyesi 



INORGANIC CHEMISTRY. 115 

probable that phenomena are constantly going on before our 
eyes, which, could we understand them, would astonish us 
still more, and at the same time afford a still stronger convic- 
tion of our ignorance, and want of penetration ? 

These considerations, while they are calculated to humble 
the pride of human intellect, by showing how little we know 
of the laws which govern even the ordinary operations of 
nature, oug-ht, by the conviction of ignorance, to prove an in- 
centive to constant observation on natural phenomena, that, 
if possible, we might arrive at the knowledge of their true 
causes. *^' 

INORGANIC CHEMISTRY. 

NON-METALLIC SUBSTANCES. 

Oxygen — 8. \ 

The name oxygen is derived from two Greek words, and 
signifies the former, or generator of acids, because it enters 
into the composition of most acid substances, and was for- 
merly considered the universal and only acidifying principle 
in nature. 

It was discovered by Dr. Priestley in 1774, and named by 
him dephlogisticated air. Its specific gravity is 1.11, air 
being 1. It is a non-conductor of electricity, like common 
air. Its electrical state is always negative, and when sud- 
denly and forcibly compressed, as in the fire-pump, already 
described, it emits light and heat. 

Oxygen may be obtained from many substances. The 
peroxides of lead, or manganese, and the nitrate and chlorate 
of potash, all yield it in abundance, when merely exposed to 
a dull red heat. 

The cheapest and most convenient substance for this pur- 
pose is black, or peroxide of manganese, in the state of fine 
powder. This, when heated in an iron bottle or gun-bar- 
rel, will yield upw^ards of 120 cubic inches of the gas to an 
ounce of the oxide. For small experiments, a gun-barrel 
may be used ; but where considerable quantities are wanted, 
a wrought iron bottle, with a neck 1 8 inches long, is the best 
instrument. 



\VIiat does the term oxygen signify 1 Who discovered this gas 1 What is the specific 
gravity of oxygen gas 1 What are the substances from which it can be obtained 1 What 
is the cheapest and most convenient mode of obtaining it 1 How many cubic inches of 
this gas will an ounce of the black oxide of manganese yield ? What are the methods 
described of extricating this gas from manganese J 




116 OXYGEN. 

l''tg.A7. "Yhe shape is represented at Fig. 47, with the addi- 
tion of a piece of gun-barrel, fitted to the mouth of 
the bottle by grinding. A tube, leading from the 
gun-barrel to the gas holder, conveys away the oxy- 
o-en as it is extricated from the mano^anese. In the 
absence of such a bottle, oxygen may be convenient- 
ly obtained by mixing, in a proper vessel, one part of 
sulphuric acid, and two parts of the oxide of manga- 
nese, and applying the heat of a lamp. The cheap- 
est and most convenient vessels for this purpose are 
Florence flasks, fitted with corks and tubes, as rep- 
i resented by Fig. 36. This, and the lamp furnace, 
'Fig. 43, together with an inverted vessel filled with 
water, constitute the apparatus necessary for the extrication 
and confinement of oxygen. 

With respect to the theory of these processes, it is neces- 
sary to state, that there are three oxides of manganese, each 
of course containing different proportions of oxygen. These 
oxides are thus constituted, the combining proportion of man 
ganese being 28, and that of oxygen 8. 

Protoxide manganese, 28, added to oxygen, 8=36 
Deutoxide 28, " '^' 12=40 

Peroxide 28, " " 16=44 

When the peroxide is exposed to a red heat, it parts with 
half a proportion of oxygen, that is, 4 parts, the number for 
oxygen being 8, and is therefore reduced to a deutoxide, 
whose number, it will be observed, is 40. The number for 
the peroxide being 44, and the loss by a red heat being 4, we 
obtain 4 grains of oxygen for every 44 grains of the oxide, 
which in bulk is nearly 12 cubic inches, making about 128 
cubic inches for each ounce of the oxide. 

When oxygen is obtained by means of sulphuric acid, the 
theoretical expression is different. In this case the peroxide 
loses a whole proportion of oxygen, and is thus converted 
into a protoxide, which then combines with the acid, forming 



What apparatus is necessary for obtaining this gas from manganese by mean^ of sul- 
phuric acid 7 How many oxides of manganese are there, and what are the pro]K)rtionj? 
of oxygen in each? Wliat proportion of oxygen does the peroxide part with at a red 
heat 7 To what oxide is the peroxide reduced by parting with a portion of its oxygen 1 
What does deutoxide mean 7 Explain the chemical chajigcs which take place when tho 
•xygcn ie obtained by means of sulphuric acid. 



/ 



OXYGEN. 117 

a sulphate of manganese, which remains in the retort. By 
this process, therefore, the peroxide yields 8 grains of oxy- 
gen to every 44 grains employed ; but in practice it is found 
that the first method is the best and cheapest. 

It will be observed, that the weight of oxygen for the deut- 
oxide, expressed above, is only 12, being a proportion and a 
half, instead of 2 proportions of that element. The oxides of 
lead and iron afferd examples of precisely the same kind. 
These facts were at first supposed to afford exceptions to the 
law of definite proportions, or rather to the atomic theory by 
which the cause of definite quantities is explained. But it 
will be remembered, as already stated, that the smallest pro- 
portions in which bodies have been found to combine by 
weight, are those by which they are represented in numbers. 
Now the smallest proportion in which oxygen has hitherto 
oeen known to combine, is in water, this proportion being as 
8 to' 1. The number, therefore, for oxygen is 8. But if it 
should be hereafter found, in the course of analysis, that oxy- 
gen unites in half this proportion, in any instance, then this 
apparent anomaly will be completely explained, for then its 
union with hydrogen, to form water, will be in two propor- 
tions, and its union with manganese, forming the deutoxide, 
will be in three proportions, &c. The fact, therefore, that 
oxygen unites in the proportion of 12 is not considered a 
valid objection to the universality of the law of definite and 
multiple proportions, but only a proof that the smallest combi- 
ning proportion of oxygen may not yet have been discovered. 

This digression seemed necessary, in order to explain, 
once for all, this apparent anomaly. 

Oxygen gas is an invisible transparent fluid, like common 
air, and has neither taste nor smell. It is sparingly absorbed 
by water, 100 cubic inches of which, take up three or four 
cubic inches of the gas. 

Oxygen has the most universal affinity of any known sub- 
stance, there being not one of the simple substances with 
which it may not be made to combine. It unites with all the 
metals, forming a very extensive class of compounds, known 
! under the name of oxides. With some of them it combines 



Wliat is said concerning the weight of oxygen for the deutoxide of manganese 7 Why 
does not the discovery, that oxygen sometimes combines in the proportion of 12, tend to 
invalidate the atomic theory 1 What is said of the taste and smell of oxygen 1 In whal 
proportion is this gas absorbed by water l What is said concerning the extensive affinity 
jf oxygen 1 



118 OXYGEN 

in such proportions as to form acids. Such is tne Cdse with] 
arsenic, molybdena, and others. With the simple combusti- 
bles, sulphur, carbon, &c., it also combines in various pro- 
portions, forming oxides and acids. With the metals sodium j 
and potassium, it enters into combination to form the alkalies} 
soda and potash. Thus the acids and alkalies, though in! 
most of their properties so entirely opposed to each other, are 
composed of oxygen united to different bases, the base of 
sulphuric acid being sulphur, and that of potash being po- 
tassium. 

The process of oxidation sometimes takes place very slow- 
ly, as in the rusting of iron exposed to the atmosphere. In 
this case, the affinity of the iron for the oxygen contained in 
the atmosphere, though constantly exerted, produces its ef- 
fects very gradually, particularly if the iron is kept in a dry j 
state ; but the oxidation is greatly facilitated if the iron is ] 
moistened with water, since then the metai absorbs oxygen ', 
from the water, as well as from the air. 

In ordinary combustion, which is nothing more than a rapid ^ 
oxidation, with the extrication of heat and light, the strong 
affinity betw^een the combustible and the oxygen is caused hy 
the great elevation of temperature. The combustible re- 
quires, in the first place, to be heated to a certain degree, 
before it will attract oxygen with sufficient force to emit heat 
and light, after which, the elevation of its temperature is con- 
tinued by the absorption of oxygen, and thus the combination 
of one portion of oxygen with the burning body causes the 
aosorption of another. 

A combustible is any substance, capable of uniting with 
oxygen, or any other supporter of combustion, Avith such ra- 
pidity, as to cause the disengagement of heat and light. In 
this sense, iron, steel, and many other bodies, though they will 
not burn in the open air, are strictly combustibles, as they 
conform to the above definition, when heated in oxygen 
gas. 

In this gas, all combustibles burn with greatly increa^d 



What are the compounds of oxygen and the metals called 1 Does it ever form acidr b) 
combining with the metals 1 When combined with the metals potassium and sodltt<ri, 
what are formed? What is said of the spontaneous oxidation, or rusting of iron 7 Wt«t 
is ordinary combustion? In combustion what causes the strong affinity between the 
burning body and oxygen 1 In kindling a fire, why is it necessary to raise the tempera • 
ture of the wood, in order to make it burn! Wliat is a combustiljle bodyl In wuat 
eense are iron, steel, and otner metals, combustibles 1 



OXYGEN. 119 

splendor ; and many substances wlilcli, l.jfore the discovery 
of this gas, could not, in any sense, belong to this class, are 
now strictly combustibles. 

The combustion of various substances in oxygen gas, affords 
experiments of the most brilliant and instructive kind. 

Among these, the combustion of iron, steel, and zinc, are 
highly interesting, not only because we are not in the habit 
of seeing metals burn, but because the first give out the most 
splendid corruscations of light, while the zinc burns with a 
light peculiar to itself 

To exhibit the combustion of iron or steel, in this gas, 
procure a piece of vvare of small size, or what is better, a 
watch spring, and wind it round a slender rod of w^ood, so 
as to coil it in a spiral form, the turns of the wire being 
about the fourth of an inch apart. Then withdraw the rod, 
and fix to the lower end of the coil a small piece of thread 
dipped in melted bees-wax, or sulphur, or w^hat is better, a 
little piece of spunk. The other end of the wire, for a few 
inches, is to be left straight, and fixed to the cork fitting the 
mouth of the bottle in which the experiment is to be 
made. 

Next, fill a clear glass bottle of a quart or more capacity 
with oxygen gas, and having set it upright, cover the mouth 
with a plate of glass, or otherwise. Then inflame the com- 
bustible on the end of the w^ire, and having removed the cov- 
er from the bottle, introduce the coil, and fix the cork in its 
place, as represented by Fig. 47. 

Pis' 47 '^^^ wire v^all burn with a light too vivid for 

the eyes to bear, throwing out the most brilliant 
corruscations in every direction. Now and then 
a globule of the melted metal w411 fall, and if 
the vessel contains water, it will leap on its 
f surface for an instant or two, being thrown up 
^by the steam into which it converts the fluid. 
:^ If the vessel contains no water, the intense heat 
^of the globule will cause it to melt the glass and 
^sink into its substance, and if the glass be thin, 
it will fuse a path quite through it, without caus- 
.no- the least fracture. 



j What is said of the brilliancy of the combustion of some of the metals 1 How is the 

I tron wire prepared for combustion in oxygen gas 1 Describe Fig. 47. Wliat causes the 
i globules of melted iron to leap on the surface of the water ? What is said of the action 
of the globules of metal on the glass 7 




120 OXYGEN. 

To witness the combustion of zinc in oxygen, first prepare 

ihe metal by melting, and pouring it while fluid into the water. 
Then place some thin pieces in a spoon prepared with a 
cork on its handle, as represented by Fig. 48, and put in the 
jv ^g midst of the zinc a small piece of phosphorus. Hav- 
^' "ing a bottle of the gas prepared as in the last experi- 
ment, inflame the phosphorus by holding the spoon 
over a lamp, and instantly introduce it into the bot- 
tle, fixing the cork in its place. The metal will burn 
with a beautiful white light, often tinged with green, 
owing to a small quantity of copper which the zinc 
contains. 

If a lighted candle be blown out and then plunged 
into a vessel of this gas, while a spark of fire remains 
in the wick, it will be relighted with a slight explosion. 
The best way of making this experiment, is, to place a 
short piece of candle in a socket, fixed to a wire, as in Fig. 49. 
In this manner a candle may be blown out and again set on 
FV 49 ^^^ ^^ dipping it into a bottle of oxygen, twenty or 
^' 'thirty times, and perhaps oftener. 
^ During combustion in oxygen gas, the oxygen com- 

bines with the burning body, and produces remarka- 
ble changes, not only on the combustible, but also on 
the gas. The combustible, on examination, will be 
found to have sensibly increased in weight, by the 
combination, while the oxygen entirely loses the pow- 
er of again supporting combustion, so that if a lighted 
candle be plunged into it, instead of burning with 
splendor as before, it is now instantly extinguished. 
These changes are readily explained by the analysis of 
the body burned, and of the gas. The iron loses its brillian- 
cy, and is converted into a dark brittle substance, easily pul- 
verised in a mortar. This is an oxide of iron, and consists 
of the iron itself united to the ponderable portion of the gas. 
If the iron is weighed before the combustion, and afterwards, 
it will be found to have increased in weight in the proportion 
of 8 parts to the 28. 



Describe the method of preparing and burning zinc in oxygen gas. What is the effect 
when a candle is blown out, and tlien instantly plunged into the gas? What effect does 
combustion produce on oxygen gas 7 What change is produced on the iron burned in it? 
Why does the oxide of iron weigh more than the metal before it was burned ? Suppose 
Uie iron and oxygen are both accurately weighed before and after the experiment, what 
effect on their weights will be produced by the combustion? 



OXYGEN. 121 

The gas on the contrary loses in weight what is gained by 
the iron, and if the vessel in which the experiment is made, 
be open at the bottom, and stands in a dish of water, the di- 
minution of the gas in volume will be indicated by the rise of 
the water in the vessel. If the gas and iron are both accu 
rately weighed before the experiment and afterwards, the sum 
of their weights will be found precisely the same, proving 
that nothmg has escaped, and that what has been lost by the 
oxygen has been gained by the iron. When other combusti 
bles are submitted to the action of this gas, though they may 
entirely change their appearance by the process, or seem to 
be dissipated and consumed, yet nothing is lost by the burn 
ing, there being in all such instances merely a change of form. 
Thus, when charcoal or diamond is burned in a confined por- 
tion of this gas, instead of losing as in the former experiment, 
the eras increases in weio^ht, that is, it is converted into car- 
honic acid gas, by a union between the oxygen of the gas, 
and the carbon of the diamond or charcoal, so that Avhat i-s 
lost by the charcoal is gained by the gas. 

In every instance, the gaseous matter which remains in 
the vessel after combustion, is unfit to support animal life. 
If a bird or any other animal be confined in a limited portion 
of atmospheric air, it soon dies, because it destroys the oxy- 
gen the air contains, by converting it into carbonic acid, thus 
leaving another portion of the atmosphere called nitrogen, 
both of which are destructive to life. (See Nitrogen.) 

If a bird be confined in a portion of oxygen, it will live 

longer than in the same quantity of atmospheric air, because 

;t is the oxygen alone which supports the respiration ; but it 

dies when the oxygen is consumed, or converted into carbonic 

, acid. But if any animal be introduced into a portion of air 

'. after its oxygen has been destroyed, or absorbed by a burn- 

'j ing body, it dies in a few seconds, unless like the frog it has 

q the power of suspending its respiration. 

\ Finally, it is proper to remember, that no animal can live 

v:7i an atmosphere which will not support combustion. 



Is any thing lost by combustion ? When charcoal is burned in a confined portion 
»f oxygen gas, what effect is produced on each 1 Into what gas is the oxygen con- 

, I'erted by the process 7 Will the gas left after combustion ever sustain animal life? 

I Why will a bird or any other animal soon die when confined in a limited portion of 
ommon air? Why will an animal live longer in oxygen gas, than in the same 

n;»ortion of common air 7 Will an animal live in air which will not support com- 

M >uation 7 



122 HYDROGEN. 

Were this fact more generally known and remembered 
vve should not every year hear of instances where lives ara 
lost by descending into old wells or cisterns. The cause o^ 
such accidents is the presence of carbonic acid, in the botJ 
toms of such cavities ; and were the precaution taken to lei 
do\vn a burning candle, before the descent of the person, alB 
danger might be avoided ; for if the flame is exting^uished 
the air will not support animal life. ' 

It has been recently reported, that throwing buckets of waj 
ter into a well, where two persons had fallen do^vn by suffa 
cation with carbonic acid gas, had been the means of savin| 
their lives. {See Carbonic Acid.) 

Hydrogen, — 1. 

The name of this gas is derived from two Greek word 
signifying the generator of water, because it enters largelj 
into the composition of that fluid. 

It was discovered by Mr. Cavendish in 1766. Its specific" 
gravity is 0.694, air being 1. — 100 cubic inches weigh 2.11 
grains, while the same bulk of air weighs 30.5 grains ; it is 
therefore about 1 4 times lighter than atmospheric air. Com- 
pared with oxygen, it is just 1 6 times lighter than that gas ; 
being indeed the lightest of all known ponderable bodies. It 
refracts light more powerfully than any other body, its re- 
fraction being in the ratio of 6.6, air being 1. Its electricity 
is positive. 

Hydrogen may be obtained by several processes, but in no 
instance without the presence of water, it being evolved only 
by the decomposition of that fluid. 

The most convenient method, is to put fragments of iron 
or zinc into a proper vessel, and pour on them two parts by 
weight of sulphuric acid, diluted with 5 or 6 parts of water. 
The hydrogen will immediately ascend through the Avater in 
abundance. 



Will air which is unfit for respiration support combustion? What precaution 
ought always to be taken, before a person goes into a well cr old cistern 7 What i» 
the derivation of the word hydrogen? What is the weiglit of 100 cubic inches ol 
this gas? WTiat is its weight when compai'ed with air? How much lighter is hy- 
drogen than oxygen ? What substance is lighter than hydrogen gas ? What is said 
of Its power to refract light ? What is the electrical state of this gas ? Can this gas bo 
obtained without the presence of water? Why ? What is the best method of obtaining 
Uiis gas 1 



HYDROGEN. 



123 




Fig. 50. Where only small quantities of 

the gas are wanted, the simple ap- 
paratus represented at Fig. 50, is 
all that is required. It consists of 
a Florence flask into which the zinc 
and acid are put, with a tube lead- 
ing under a bell glass, or large 
^ tumbler filled w^ith water, and in- 
verted in a dish of the same fluid 
^:& Zinc for this purpose is better than 
iron, and is easily prepared by melting, and while fluid, pour- 
ing it into water. 

The production of the hydrogen depends on the decompo- 
sition of the water which is effected by the united action of 
the metal and acid. The metal having an attraction for oxy- 
gen, obtains it from the water; this forms an oxide of the 
metal which is instantly dissolved by the acid ; the surface o 
the metal is thus left clean, and exposed to the water, from 
which it attracts another portion of oxygen, which is dissol- 
ved as before. Meanwhile the hydrogen being thus detachea 
from the oxygen, absorbs caloric, and is evolved in the form 
of hydrogen gas. 

Hydrogen may also be obtained by passing the vapor o 
water through a hot iron tube. In this case, the oxygen of 
the water combines with the iron, while the hydrogen is set 
free. 

Place a gun barrel across a furnace so as to heat it red hot. 
Connect to one end of the barrel, by means of a tube, a re- 
tort containing water, and placed over an Argand lamp : and 
to the other end of the barrel fix a tube, leading under a ves- 
sel of water, inverted in a water bath. Then make the water 
in the retort boil, so that its steam may pass into the gun bar- 
rel, and hydrogen will be evolved, and will pass into the 
inverted vessel. 

Hydrogen, when obtained by either of these methods, is not 
quite pure, but contains a little sulphur or carbon. For par- 
ticular purposes it may be purified by passing it through a 
solution of pure poMsh in water. 

In this state hydrogen is without colour, taste, or smell. It 



On what does the production of hydrogen depend 1 Explain the chemical changes 
which take place during the production of this gas. By what other method may this gas 
be obtained 1 How does the red hot gun barrel decompose the water 7 Is hydrogen a 
compound or an elementary bodv 



124 HYDROGEN. 

•s, SO far as is known, an elementary body, having iesisted all 
attempts to resolve it into more simple parts. 

It is inflammable, but not a supporter of combustion. If a 
lighted candle be introduced into a vessel of this gas, the 
flame is instantly extinguished, but in passing into the gas, it 
inflames that portion which is in contact with the atmosphere. 
This shows that the combustion of hydrogen requires the aid 
of oxygen which it absorbs from the atmosphere as a supporter. 

This experiment may be made by inverting the vessel con- 
taining the hydrogen in the open air, its levity preventing it 
from escaping downwards. In this state it will be seen to 
burn only on the lowest surface. But if the vessel contain- 
ing it be turned upright, the whole will escape in a volume 
of flame. 

Hydrogen is the gas with which balloons are charged, and 
being about fourteen times lighter than common air, if the 
balloon is large, it ascends with great force. The principle 
on which balloons ascend, is the diflference of specific gravity 
between the balloon as a w^hole, consisting of hydrogen, and 
the apparatus containing it, and the same bulk of atmosphe- 
ric air. It is the same principle that makes a cork rise through 
water, or a leaden bullet through quicksilver. 

The principle of balloons may be illustrated thus. Fill a 
bladder, or a gas bag, furnished with a stop-cock, with hy- 
drogen gas ; attach to the stop-cock a tobacco pipe, or what 
is better, one of metal. Then dip the bowl of the pipe into a 
solution of soap, and form bubbles by pressing the bladder. 
These bubbles being detached from the pipe, will rise rapidly 
through the air. 

When hydrogen is mixed with oxygen and inflamed, the 
mixture detonates violently. The best proportions are two 
parts of the hydrogen and one of oxygen by volume. If soap 
bubbles of this mixture are touched with a candle when float- 
ing in the air, they give a report as loud as a pistol, but much 
more sharp and stunning. 

A loud report is also given when the hydrogen is mixed 



' When a lighted candle is plunged int-o this gas, does it continue to bum, or is it extin 
guished 1 As the candle passes into the gas, what pait of it is set on fire ? How is this 
experiment best made 1 Why does the hydrogen burn only on the surface 1 With what 
gas are balloons filled 7 On what principle do balloons ascend 1 How may the principle 
of balloons be illustrated 1 What is the consequence of firing a mixture of hydrogen and 
oxygen 1 What proportions of each make the loudest report % 




HYDROGEN. 125 

With common air, mstead of oxygen. The best proportions 
are about three of the air to one of the hydrogen. 
Fig.5\. This experiment may be varied by means of the 
hydrogen gun, Fig. 51. IC consists of a tin vessel, 
holding about a pint, the lower end being closed, and 
the upper end left open and iitted with a cork, a small 
I orifice being made toward the lower end, as seen in 
[the figure. 

Having filled this vessel about one third with water 
dolose the small orifice with the thumb, and let in hy- 
drogen until the water is displaced. Thus, the vessel 
will contain three parts of air, and one of hydrogen. 
The cork being put rather loosely in its place, the mixture 
is fired by raising the thumb, and applying a lighted taper to 
the orifice. The cork will be driven out with violence, at- 
tended with a loud report. 

When a jet of hydrogen is burned at the end of a tube 
with a fine bore, and with a large tube of glass, porcelain, or 
metal, musical tones are produced, which are grave or acute 
in proportion to the size or kind of tube employed. 
Fig.^2. This pleasing experiment may be performed by 
placing the materials for making hydrogen, in a 
convenient vessel, furnished with a tube, as in Fig. 
52. Or the tube may be connected with a reser- 
voir of gas already collected. The manner of hold- 
ing the large tube to produce the musical tones is 
^ shown in the figure. 

Hydrogen cannot be breathed without deleterious 
(^ efTects, though it is not immediately fatal to animal 
(^\ life. 

The action of platinum sponge on hydrogen is 
singular, and highly curious. When a jet of this 
_ gas is directed on a few grains of the sponge, both 
being cold, and in the open air, the latter immediately be- 
comes hot, and in a moment glow^s with a red heat, setting 
fire to the hydrogen. 

Platinum sponge is prepared by dissolving the metal m 




What are the best proportions for mixing hydrogen and air for the same purpose ? 
Describe the method of using the hydrogen gun, Fig. 51. How are musical tones pro 
ducesi by the buming of hydrogen ? Explain Fig. 52. Is hydrogen a respirable gas 1 
What effects does it produce when breathed 1 What phenomena are produced when hy 
dr jgen is thrown in a stream upon platina sponge I How is platina sponge prepared 1 

11* 



i26 HYDROGEN. 

niiro-muriatic acid, that is, a mixture of one part of nitric to 9f 
parts of muriatic acid. Ammonia, or muriate of ammonia, w 
added to this solution, which produces a yellow precipitate 
When this precipitate is exposed to a red heat in a crucible 
the acids and ammonia are driven off, and there remains pure 
platinum, in the form of a delicate spongy mass. Another 
method of obtaining the sponge, is to throAV the yellow pre- 
cipitate on filtering paper, and Avhen the liquid has passed 
through, to dry the paper, and introduce it, w4th the adhering 
precipitate, into the crucible. 

This curious effect of the action between platina sponge 
and hydrogen, was discovered by Professor Dobereiner, of 
Jena, who invented the following method of producing an 
instantaneous light by its means. 

Fig. 53. The two vessels, a and Z>, Fig» 

Q 53, are of glass ; a is prolong- 

r-^—^ ed in the form of a tube, and 

is fitted to the mouth of b, by 
grinding, or cement, so as to 
be air tight. The lewder part 
of ^ reaches nearly to the bot- 
(J torn of &, and is encompassed 
with a strip of zinc. Sulphuric 
acid, diluted w^ith five or six 
parts of w^ater, being placed 
in. b, a is fixed in its place, as 
seen in the figure. Hydrogen 
is evolved by the action of the 
acid on the zinc, and pressing 
upon the fluid, (which must 
fill only about one half of b.) 
drives it up the tube into a. The stopper of a, is conical, and 
rises to let the air from that vessel escape. When so much 
gas has been evolved as to press most of the acid up into a^ 
and consequently to remove it from the zinc, the chemical 
process will cease, leaving b nearly filled with hydrogen. 
The brass tube d, is cemented to the neck c, and furnished 
with a stop-cock. The box e, contains the platina sponge at 
the end of the tube. 

When a light is wanted, nothing more is necessary than to 




I 



Explain Fig. 53, and show how hydrogen is produced, and in what manner it is thrown 
upon the sponge. Why does not the acid constantly act upon the zinc 7 



HYDROGEN. l27 

open the stop cock d, and let a jet of the gas blow upon the 
sponge, which becoming immediately red hot, a match, and 
then a candle may be lighted. By permitting the hydrogen 
to escape, the acid again comes in contact with the zinc, and 
thus another portion of the gas is formed, and retained until 
wanted. 

Protoxide of Hydrogen 9. *** 
1 p. Oxygen 8+1 p. Hydrogen 1, 

Water. 

It is only necessary to remark in respect to the above ab- 
breviations, that the number for water, as already explained, is 
, being composed of 1 proportion of oxygen 8, and 1 propor- 
tion of hydrogen 1. The same method being observed with 
respect to the other substances to be described, the student 
has only to notice the numbers affixed to the names of each 
substance, and he at once becomes acquainted with the pro- 
portions and composition of each compound, and the number 
by which the compound itself is represented. This method, 
it is thought will not only be found highly convenient, but 
will also greatly facilitate the acquirement of a proper know- 
ledge of chemical equivalents, a subject, as formerly remark- 
ed, of great importance to the student in the present state o* 
the science. 

It has been stated that water, by analysis, is composed of 
two parts of hydrogen, and one of oxygen, by volume, and 1 
part hydrogen, and 8 oxygen by weight. 

Having described the properties of these two gases sepa- 
rately, it now remains to demonstrate by synthesis, that is, by 
the combination of these gases, that water is the product. 

It may be seen by a very simple experiment, that when 
hydrogen is burned, water is formed. 



When one portion of the gas escapes, in what manner is another portion generated? 
Wliat is signified by the numbers affixed to water, oxygen and hydrogen 7 With what 
does the student become acquainted by observing the numbers affixed to names of the 
elements, and of their compounds 1 By analysis, what is the composition of water, by 
weight and measure 7 By what simple experiment may be shown that when hydrogen 
vi burned, water is formed 1 




128 WATER, 

Fill with hyrfrogen a blad 
der, furnished with a stop 
cock, and small tube. In 
flame the hydrogen at the 
end of the tube, and intro- 
duce the flame into a dry 
glass globe with two open- 
ings, as represented at Fig. 
54. As the gas burns, the rarefied and vitiated air will pass 
ofT at one of the openings, while the other admits fresh air to 
support the combustion. In a few minutes the inside of the 
globe will be covered with moisture, and by continuing the 
experiment, water will run down its sides, which may be 
tasted or otherwise examined. The same experiment may 
be made with a large glass tube instead of a globe. In this 
experiment, it is supposed that the combustion of the hydro- 
gen is supported by the oxygen of the atmosphere, and there- 
fore nothing can be known of the proportions in which they 
unite. Nor would it be absolutely certain by this experiment 
that it was the oxygen of the atmosphere which combined 
with the hydrogen, and supported its combustion. 

But when the two gases are confined, each in a separate 
gasometer, and burned together in an exhausted vessel, the 
result will not only demonstrate to the senses that water is the 
product, but will also show the exact proportions of each ele- 
ment by weight and measure. 

For this purpose two graduated gasometers contain the two 
gases, each being furnished with a tube, leading to the glass 
globe. Fig. 55. Before the experiment begins, this globe is 
connected withan air pump by the screw 
c, and completely exhausted of air, and 
then accurately weighed. It is then 
connected with the two gasometers which 
contain the gases by the pipes cl and e. 
When every thing is thus prepared, the 
stop-cock d is opened, and a small stream 
_of hydrogen let in, which is instantly in- 
"flamed by an electrical spark from the 
conductor a, this being of course connected with an electrical 




k 



Is it ab£K)lutely certain by this experiment, that it is the oxygen of the atmosphew 
which unites with the hydrogen to form water 1 How may it be demonstrated that the 
combustion of hydrogen and oxygen form water 1 Describe the apparatus represented 
by Fig. 55j and explain how the two gases axe brought together, and how inflamed? 






WATER. l29 

machine. The oxygen is then admitted, by turning the stop- 
cock, e, and thus the combustion of the hydrogen is supported. 
At the end of the process, the graduated gasometers shew 
exactly the volume of each gas consumed, and as the weight 
of 100 cubic inches of these gases are known, it is easy to 
compute the weight of the volumes consumed, and by weigh- 
ing the globe to compare it with the weight of water produced. 
By such experiments made with every attention to accura- 
cy, together with that before described, of weighing the gases 
by means of exhausted vessels, Fig. 45, it is proved, that 
hydrogen and oxygen unite in the proportions of two of the 
first, to one of the last, by volume ; and in the proportions Ox 
1 and 8, by weight ; that the sole product of the combustion 
of the two gases is water, and that the weight of the water 
is just equal to the combined weights of the two gases. In 
" is manner has the constitution of water been demonstrated 
Beyond all doubt or controversy. 

Compound Blowpipe. When hydrogen and oxygen are 
burned together, in the proportions in which they form water, 
a most intense heat is produced. The compound blowpipe, 
the instrument by means of w^hich the combustion of the two 
gases is regulated for this purpose, was invented by Professor 
Hare, of Philadelphia, in 1801. The apparatus consists of two 
pipes, which convey the gases from two gas-holders, to another 
9hort pipe, at the end of which their combustion takes place. 
' The principle of the com- 

pound blowpipe will be under- 
stood by Fig. 56. The two 
brass pipes c and d, are con- 
nected with the gas-holders a 
and b, by coupling screws, 
which fix their lower ends to 
short tubes furnished with stop- 
cocks, as seen in the figure. 
These stop-cocks are for the 
convenience of confining the 
gas in the gas-holders, when 
the blowpipe is not in use, and 



• 



Hg. 56. 





At the end of the process, how is it ascertained what proportion of each gas has been 
eousumed, and how much water formed 1 What has been proved by such experiments 
in respect to the quantities and proportions of the gases consumed, and quantity ot water 
formed 7 What is said of the intense heat produced by the combustion of hydrogen and 
oxygen 1 Wliat is the instrument called by which tlie combustion cf the two gases is 



130 COMPOUND BLOWPIPE. 

for other purposes connected with the pneumatic cistern. 
The two upper stop-cocks are designed to regulate the quan- 
tity of gas from each pipe, so as to produce the greatest heat, 
and also to stop it entirely while makmg experiments. 

The gas-holderr^ a and b, are two boxes of painted tin, open 
at the bottom, and made to fit a cistern of wood, about five 
, feet long, containing* water. These boxes are fixed in their 
places, at each end of the cistern, by buttons, so that they can- 
not rise when filled with gas. They may be two and a half, 
or three feet deep, and two feet wide, or of any other size, 
according to the extent of the experiments proposed. The 
cistern must be several inches deeper than the boxes, so that 
the water will rise above them. 

The two pipes convey the two gases separately to the point ^ 
e, where they are soldered together, and on their united points JB 
is screwed a platina or silver tip, ha^dng a single orifice, a,t ^^' 
the end of which their combustion is effected. If the tip is 
of silver, it should be large, and care taken not to include il 
in the cavity of the charcoal support, while making experi- 
ments, otherwise it will be melted. 

Having such an apparatus, ready, the gas-holders are put 
in their places, (the blowpipe being removed, until every 
thing is prepared for experiment,) and water is poured int6^| 
the cistern, the stop-cocks being open for the escape of the air. 
When the cistern and boxes are full of water, the stop-cocks 
are closed, the blowpipe screwed on, and the two gases are 
conveyed under the boxes by tubes, coming from the vessels 
where the gases are evolved. One of the boxes being filled 
with hydrogen and the other with oxygen, the blowpipe is set 
in action by turning the stop-cock connectea with the hydro- 
gen, and setting the gas on fire as it issues from the tip. ^The 
oxygen is then admitted, when the flame of the hydrogen 
will become less, beicig reduced to a small blue flame, which 
gives little light, and to the eye appears insignificant, and 



i 



regulated for this purpose 1 Explain Fig. 56, and show the uses of the two tubes, the 
stop-cocks, and the platina tip, &c. In filling the cistern, why are the etop-cocks left 
open 7 What is said of the smallness of the flame, arjd the intensely heating powei of 
Uiis blowpipe % 



PROPERTIES OF WATER. 131 

f dally incapable of the calorific effects attributed to this cele- 
brated machine. But the student who had never witnessed 
its powers, will be struck with astonishment, when he finds 
that a piece of iron, or copper wire, held in this little flame, 
burns with nearly the same facility, that a cotton thread con- 
sumes in a candle ; and that a piece of tobacco pipe not larger 
than a kernel of corn, will give a light, from which he will 
instantly be forced to cover his eyes. 

The compound blowpipe melts the most refractory substan- 
ces, and even dissipates in vapor those which are infusible by 
the best furnaces. No means hitherto discovered, with the 
exception of the galvanic battery, produce calorific effects so 
intense as this blowpipe. 

Fig. 57, The pneumatic cistern 

~ above described is represent- 

ed at Fig. 57, with the blow- 
pipe in its place. For schools 
or private experiments, per- 
r,, ,„ ,x, haps this is as cheap and 

n "" — '. . 

f IL *^' I [Lconstructed ; since it serves 

I L the purpose of gasometers for 
^»te the blowpipe, and a cistern for experiments on all the gases 
wtere a water bath is employed. It is believed, after having 
had occasion to direct the construction of several cisterns for 
the above named purposes, that the following dimensions are 
sufficient. Length of the cistern, 5^ feet ; depth, 2j- or 3 
feet ; width, 2 feet ; gas-holders or boxes, 2 feet square. The 
cistern to be made of pine boards, and well painted on both 
sides before it is used. The frame and legs on which it stands, 
mustT)e separate from the cistern, about 18 inches high, and 
furnished with rollers. Such an apparatus, including the 
blowpipe and boxes, costs about 14 dollars. 

• . Properties of WoAer. 

ft* 

It is unnecessary to describe the common properties of a 
fluid w^hich is so universally knowu, that neither man nor 
animal can exist without it. The purest water not having un- 
dergone distillation, is that which falls from the clouds.— It 



Is there any means of producing a more intense heat than that produced by the cora 
pound blowpipe 1 Explain Fig. 57. What water is purest without distillation 1 




132 PROPERTIES OF WATER, 

is transparent, and without either taste or smell ; and being 

Perfectly bland and neutral, it is to all animals, whose tastes 
ave not been vitiated, the most agreeable of drinks. 
The weight of water, as already shown, is the standard by 
w^hich the weight or gravities of all solids and liquids are es- 
timated. The weight of a cubic foot of pure water is 1000 
avoirdupois ounces. A cubic inch of this fluid weighs, at the 
temperature of 60°, 252.52 grains, and consists of 28.00 
grains of hydrogen, and 224.46 grains of oxygen. By divi- 
ding 224.46 by 28.06, it maybe seen how nearly these gases 
unite in the proportions of 1 and 8 to form water. The weight 
of water, when compared with that of air, is as 828 to 1. The 
efl!ect of temperature upon liquid water is distinguished by a 
peculiarity of a vBry striking kind, and exhibits a departure 
from the general laws of nature, for a purpose so obviously 
wise and beneficent, as to afford one of the strongest and most » 
impressive of those endless proofs of design and omniscience* 
in the frame of creation, which it is the most exalted plea- ^ 
sure of the chemist, no less than of the naturalist, to trace 
and admire. " All liquids, except water, contract in volume, 
as they cool down to their points of congelation ; but the 
point of the greatest density in water is about 40°, its freez-^ 
ing point being 32°." As its temperature deviates from this 
point, either upwards or downwards, its density diminishes ; 
or in other words, its volum.e increases. This peculiar law 
is of much greater importance in the economy of nature than 
might at first be supposed. The cold air which rushes from 
the polar regions progressively abstracts the heat from the 
great natural basins of water, or lakes, till the whole mass 
is reduced to 40° ; but at this point, by a wise Providence, 
the influence of the atmosphere no longer has this effect ; for 
the superficial stratum, by farther cooling, becomes specifi- 
cally lighter, and instead of sinking to the bottom, as before, 
and displacing the warmer water, it now remains at the sur- 
face, becomes converted into a cake of ice, and thus preserves 
the water under it from the influence of farther cold. 



To what animals is water the most agreeable of all drinks 1 What is the weight of ft 
cubic foot of pure water 1 What is the weight of a cubic inch of water 1 How may i| 
be proved that the weights of hydrogen and oxygen in water are in the proportions of ] 
to 8 ? What is the weight of water when compared to that of air 7 At what tempera- 
ture is water at its greatest density? Wlien water is above or below the temperature of. 
40 degrees, how is its bulk affected 7 In what respect is the expansion of water l*;: 
freezing, if great consequence to man 7 



OXYGENIZED WATER. 133 

If, like mercury, water continued to increase in density to 
Its freezing point, the cold air would continue to rob the mass 
of water of its heat, until the whole sunk to 32°, when it 
would immediately congeal into a solid mass of ice to the bot- 
tom, and thus every living animal it contained would perish. 
In the northern or southern temperate zones, such masses of 
ice would never again be liquefied ; a striking proof of the 
beneficence and design of the Creator in forming water with 
such an exception to the ordinary laws of nature. 

Water, in its natural state, always contains a quantity o. 
air. This may be show^n by placing it under the receiver of 
an air pump, for as the air is remo\ied from the receiver, bub- 
bles will be seen to rise from the water. The air in w^ater is 
found to contain a larger proportion of oxygen than the com- 
mon air of the atmosphera The lives of all such fishes as 
live entirely under the water, depend on the quantity of oxy- 
gen it contains, for no animal can live and move where oxy- 
gen does not exist. 

Deutoxide of Hydrogen, — 17. 
2 p. Oxygen 16+ 1 P- Hydrogen, 1. 
Oxygenized Water, 
^ Water, in the scientific language of chemistry, is the prot- 
oxide of hydrogen; being composed of hydrogen, with one 
proportion of oxygen. [See Nomenclature.) It was supposed 
that hydrogen was incapable of a farther degree of oxygen- 
ation, until 1818, when Thenard, a French chemist, showed 
that by a certain intricate process, hydrogen could be made 
to combine with another dose of oxygen, and thus a new 
compound was formed, called deutoxide of hydrogen. 

This compound is formed in precise accordance to the law 
of definite and multiple proportions, and consists of 2 propor- 
tions of oxygen and 1 of hydrogen, as stated at the head of 
this section. It is a highly curious and interesting compound. 
In some of its properties, it exactly resembles w^ater, being 
inodorous and colourless ; but in others, it is remarkably differ- 
2ni. It is corrosive to the skin, w^hich it turns white, and to 



If water, like mercury, had its density increased by cold to 32 degre-es, what would be 
he consequence, on large bodies of this fluid 1 What is said of the beneficence and de- 
ign of forming water with this exception to the ordinary laws of nature ? How is it 
hown that water always contains air % How does the air in water differ from common 
ir'J Wliat is the scientific name of water 1 What is deutoxide of hydrogen 7 What 
je the properties of oxygenized water ^ How does this compound differ from common 
rater ] 



*34 NITROGEN. 

the tongue it is sharp and biting, and leaves a peculiar me- 
tallic taste in the mouth. 

At the temperature of 58°, it is decomposed, oxygen gaji 
being evolved in abundance. It is therefore necessary, in 
the summer season, to keep it surrounded with ice. It is also 
decomposed and turned into common water by nearly all the 
metals, and most rapidly by those which have the strongest 
attraction for oxygen. Some of the metallic oxides produce 
the same effect, Avithout passing into a higher degree of oxi- 
dation, a fact which has not been satisfactorily explained. 
The metals, silver and platinum, in a state of fine division, 
decompose this water, when thrown into it, with such energy 
as to produce explosions. The same effect is produced by 
the oxides of silver, gold, mercury, manganese, and several 
other metals. 

Nitrogen. — 14. 

This gas was formerly called azote, which signifies life 
destroyer, because no animal can live when confined in it. 
But the same epithet might be applied to several other gases, 
with equal propriety; and therefore, being the basis of nitric 
acid, it is more properly called nitrogen. As the atmosphere 
is composed of fourfifths of nitrogen, this gas may be obtained 
by placing a mixture of iron filings and sulphur, a little 
moistened, in a confined portion of air, as under a bell glass, 
over water. The mixture will absorb the oxygen from the 
air, and leave the nitrogen nearly pure. It may also be ob- 
tained by burning a piece of phosphorus in a vessel of air, 
inverted over water. The phosphorus forms phosphoric acid 
with the oxygen of the air, which acid is absorbed by the 
water, thus leaving the nitrogen remaining in the vessel. 

Nitrogen is transparent, and without taste or smell, like 
common air. It is arranged as a simple body, though there 
are reasons for believing that it is a compound. 

It is destructive to animal life, and is a non-supporter of 
combustion. A lighted candle plunged into it, is instantly 
extinguished, and any animal soon dies when confined in it 



At what temperature is this compound decomposed 1 Why do the metals decompose 
this kind of water ; and what do they absorb from it 7 What was the former name of 
nitrogen 1 What does azote signify 1 Why is it now called nitrogen 7 How may nitro- 
gen be obtained 1 How is gas obtained by means of iron filings and sulphur 7 How ia 
nitrogen obtained by means of phosphorus 7 What are the properties of this gas? 



ATMOSPHERE. 135 

Yet it exerts no injurious influence on the lungs, the priva- 
tion of oxygen being the sole cause of death. 

Its specific gravity is a liule less than that of atmospheric 
air, nitrogen being 0.9722, air being 1000. One hundred 
cubic inches weigh 29.7 grains. 

When combined with oxygen in certain proportions, it 
forms nitric acid. Nitrogen exists in all animal substances, 
and in such plants as putrefy with an animal odour, as caK 
tage and mushrooms. 

TVie Atmosphere. 

The air which we breathe is composed of 20 parts of oxy- 
gen, and 80 parts of nitrogen, to every 100 by volume. 

These proportions are found never to vary, except from 
local causes. Gay Lussac, in an aerial voyage, carried with 
him an exhausted bottle, closely corked, and when at the 
height of nearly 22,000 feet from the earth, he uncorked his 
bottle, and let in the air. It was then closely corked again, 
and brought to the earth. On examination, this air was 
found to contain precisely the same proportions of the two 
elements as that taken from the surface of the earth. Speci- 
mens of air have also been brought from Chimborazo, Mount 
Blanc, from the deserts of Africa, and from the midst of the 
oceans, and on analysis, they have all been found to contain 
the same proportions of the two gases. 

These proportions are found by experiment to form the 
most agreeable air for respiration, and to be best fitted for 
the support of animal life. Animals confined in air, contain- 
ing more than the ordinary proportion of oxygen, have their 
respiration hurried, and become feverish, by over excitement ; 
while those confined to air ^vhich contains a less proportion 
of that gas, become languid and faint, from the want of its 
stimulating effects. 

Besides these two gases, the atmosphere contains variable 
portions of carbonic acid gas, and aqueous vapor. The car- 

In what manner does nitrogen destroy life? Is the specific gravity of nitrogen 
greater, or less, than that of atmospheric air 7 With what substance does nitrogen 
form nitric acid 1 In what vegetables is this gas found? What is the composition 
of atmospheric air 1 What is said of the constancy of these proportions 1 From 
what parts of the world have specimens of air been analysed, and found to contain the 
same proportions of the two gases ? What is the effect of a greater proportion of oxy. 
gen than common air contains on the animal system 1 What is the effect of a less pro- 
|K)rtion on the system 1 Poes the atmosphere contain other gases besides oxygen and 

trogen? 



136 ATMOSPHERE. 

bonic acid seems always to be present, since Saussure found 
it in the air of Mount Blanc, taken from the height of 16,000 
feet above the level of the sea. Its proportion never exceeds 
one part in a 100, in freely circulating air ; and it generally 
amounts to only 1,1000th or 1,2000th part of the whole. The 
proportion of aqueous vapor is also exceedingly variable, but 
seldom exceeds 1 part in 100. 

The air of particular situations, is also found to contain 
small quantities of carburetted hydrogen, or inflammable gas, 
and of ammonia; but these are not constant. 

It has been a question among chemists, whether the tw^o 
gases composing the atmosphere are simply in a state of mix- 
ture, or w^hether they exist in a state of chemical combina- 
tion. Mixture has commonly been distinguished from com- 
bination, by the spontaneous separation of the ingredients or 
the former. But, although oxygen is specifically heavier 
than nitrogen, no such instance has been found to occur. 

Air, confined in a long tube standing vertically for many 
months, w^as found to contain the usual proportion of oxygen 
in its upper part. The proportions of its constituents are 
also definite, like those of energetic combinations. By 
weight, there are two proportions of nitrogen 28, with 1 of 
oxygen 8. And by volume 4 parts of the first, 80, to one of 
the latter, 20, in the 100, thus making the simple proportions 
of 4 to 1. 

It has, however, been found that other gases of difTerenl 
specific gravities mix with entire uniformity Avhere it is known 
that no chemical union exists betw^een them. Thus, if one ves- 
sel be filled with carbonic acid gas, and another w4th hydro- 
gen gas, the latter being placed over the former, with a tube 
communicating between them, the two gases will mix with per- 
fect uniformity in a few hours. In this instance, a part of the 
carbonic acid, though 22 times as heavy as the hydrogen, is 
found to have ascended into the upper vessel, while a part ol 
the hydrogen, though 22 times lighter than the acid gas, de- 
scends into the lower one. The cause of such an intimate 
mixture, under such circumstances, and without the influence 

What other gas is always found in the air 1 What gases are occasionally found, their 
presence depending on local circumstances 1 What reasons are there to believe that air 
is a chemical compound 7 What singular fact is mentioned in respect to the mixture 0/ 
carbonic acid and hydrogen, through a tube 7 What does this fact show with respect to 

he uniform mixture of the elements of the atmosphere without a chemical union 1 What 
does the facility with which oxygen is abstracted from the atmosphere tend to show in 

tsiect to this chemica. mion 1 



ATMOSPHERE. 137 

of chemical attraction, has not been explained. But the fact 
is sufficient to show, that the uniform mixture of the consti- 
tuents of the atmosphere may be accounted for, without a 
chemical union. The facility, also, with w^hich oxygen is 
abstracted from the atmosphere is against a chemical union. 
Thus, rain water contains a considerable portion of oxygen, 
besides a portion of atmospheric air. But the attraction of 
water for oxygen, is not supposed sufficient to overcome a 
chemical combination, and therefore did such a combination 
exist in the atmosphere, oxygen would not be found in water 
under such circumstances. 

On the whole, it is most probable, that the constituents of 
the atmosphere exist in a state of mixture, and not in a state 
j of chemical union. 

I The oxygen of the atmosphere being the principle which 
supports life, and flame, it is obvious that large quantities of 
this gas must be consumed every day, and therefore that its 
quantity must dimmish, unless there exists some source from 
which it IS replaced. The quantity consumed, however, 
must be exceedingly small, in a definite period of time, when 
compared with the whole ; for the atmosphere not only en- 
j tirely surrounds the earth, but extends above it, at every point, 
I about 45 miles. Now, when we consider how small a pro- 
^ portion of this immense mass, comes into contact with ani 
mals or fires at any one time, and that it is only these small 
portions that become vitiated, we may suppose that ages 
would elapse before any difference could be detected in the 
quantity of oxygen, even were there no means of replenish- 
ment provided. 

But the wisdom and design of Deity which the study of 

, nature every where detects, and which as constantly seems 

I ordained for the benefit and comfort of man, has not left so 

important a principle as that of vital air to be consumed, with- 

; out a source of regeneration. 

j It appears from experiments, that vegetation is the source 

I from which the atmosphere is replenished with oxygen, and 

so far as is known, this is the only source. Growing plants, 

during the day, absorb carbonic acid from the atmosphere, 



On the whole, is it most probable that the elements of the atmosphere exist m a state 
of mixture, or in that of a chemical union 1 What is said of the quantity of oxygen 
consumed by aniinals, and flame, when compared with the whole, which exists in tlie 
atmosphere ? From what source is the atmosphere replenished with oxygen 1 



38 ATMOSPHERE. 

decompose the gas, emit the oxygen of which it is in pari 
composed, and retain the carbon to increase their gro\vth. — 
(See Vegetation.) 

We have seen, under the article Oxygen, that when wood 
or carbon is burned, that oxygen is thereby converted into 
carbonic acid gas, and a greater or less propoition of this gas 
contained in the atmosphere may be attributed to this source. 
Here, then, we are able to trace another instance of the won- 
derful oi;der and design of Omnipotence. The destruction 
of plants by burning, while the process absorbs the oxygen 
from the air, furnishes carbonic acid, v/hich in its turn, is de- 
composed by growing vegetables, the carbon being again 
converted into wood, while the oxygen goes to replenish the 
loss created by the burning, and to purify the atmosphere for 
the use of man. 

Jhkr 

NITROGEN AND OXYGEN. 

In addition to the reasons formerly assigned for supposing 
the atmosphere not to be a chemical compound, may be ad- 
duced the fact, that most other combinations of nitrogen and 
oxygen produce corrosive or noxious substances. 

Five such compounds are known to chemists, and they all 
admirably illustrate the changes produced by chemical com- 
binations, as already noticed under the article Affinity. They 
also confirm the truth of the doctrine of multiple proportions, 
having been adduced, as illustrations of this principle, under 
the same article. Some of the most material properties of 
each of these compounds will be stated, beginning with that 
containing the least proportion of oxygen, and ending with 
that containing ihe most. 

Protoxide of Nitrogen. — 22. 

1 p. Nitrogen 14X1 p. Oxygen 8. 

Nitrous Oxide. 

The best method of obtaining this gas is by fusing a salt 
called nitrate of ammonia. This salt may readily be formed 



How do plants obtain the oxygen which they emit 1 Whence comes the carbonic acid 
gas which plants decompose 1 Wha.i is said of the wonderful order and evident design 
of Providence, in making the destruction of plants the means of replenishing the air 
with oxygen ? Wliat is said of the compounds of nitrogen and oxygen in reference to 
the chemical nature of the atmosphere ? What do these compounds illustrate 7 What 
is the signification of protoxide 7 What other name is there for protoxide of nitr.^en ■* 
How is this gas obtained 1 



NITROGEN AND OXYGEN. 139 

'^ymixing carbonate of ammonia with nitric acid (aquafortis) 
diluted with four or five parts of water, and then evapora- 
ting the solution by a gentle heat. The ammonia should be 
added in small lumps until the effervescence ceases ; and the 
evaporation continued until a drop of it, placed on glass, con 
cretes. 

Having prepared the salt, the nitrous oxide or exhilarating 
gas may be procured from it, and its effects by respiration 
tried by the following simple means, when no better appara- 
tus can be obtained. 

Prepare a Florence flask, as shown at Fig. 36, and into 
this put four or five ounces of the nitrate of ammonia. For 
a gas holder, fit to a large stoneware jug a cork pierced with 
two apertures with a burning iron; into one of the apertures 
pass a tube of glass or tin, so that it shall reach nearly to the 
bottom when the cork is in its place, and stop the other ori- 
fice with a cork. 

For a pneumatic cistern, take a common wash tub, and fit 
to it a strip of board passing through the middle, and about 
four inches from the top, so that w^hen the tub is filled with 
water, the board will be covered. Through the board cut a 
hole to receive the neck of the jug, so that it will stand in- 
verted. 

Having prepared things in this manner, fill the jug with 
water, and invert it in the tub, also previously filled with wa- 
ter. Then bend the tube belonging to the flask, so that it will 
enter the mouth of the jug, while the flask itself stands on a 
ring of the lamp furnace, and apply a gentle heat. 

If no lamp furnace is at hand, the flask maybe suspended 
by a wire or string, and heated by a common lamp, or a few 
coals. The salt will soon melt and become fluid and trans- 
parent, when the gas will be extricated in abundance. When 
the jug is nearly full, which will appear by the sound of the 
bubbles, slip the hand under its mouth, and having set it up- 
right, immediately put the cork with the tube through it, in 
its place. As the nitrous oxide sometimes contains a mix- 
ture of nitric oxide, or deutoxide of nitrogen, which is danger- 
ous to respire, but which is absorbed by water, it is safest 



flow is nitrate of ammonia formed 1 Having prepared the salt, in what manner is the 
gas extracted from it 1 In what manner may a temporary gas holder and water bath bs 
prepared 7 Having prepared the gas holder, or jug, and the water bath, or i\x\ Aow will 
you proceed to fill the jug with gas? How will you know when the iug is full o<' gas 
What gas is sometimes mixed with the nitrous oxide % 



140 NITROGEN A.ND OXYGEN. 

before the gas is respired to let it stand an hour or two, Arjth 
the water remaining in the jug. 

To respire the gas, prepare a bladder, or oiled silk bag, by 
attaching to it a tube which fits closely to the second aper- 
ture in the large cork, and having squeezed all the air out Oi 
the bladder, or bag, remove the small cork and pass in the 
tube. 

Next pour such a quantity of water into the jug through 
the long tube as it is desired to obtain gas in the bag. Now 
the gas cannot escape through the long tube, because its 
lower end is in the water, nor can it escape through the mouth 
of the jug, this being closed by the cork ; it therefore passes 
into the bag. When this is full, withdraw the tube from the 
jug, and having expired, or thrown the air from the lungs, 
close the nose with one hand, and with the other apply the 
tube to the lips and breathe the gas from the bag into the 
lungs, and from the lungs to the bag. Sir H. Davy respired 
12 quarts, but the medium dose is from 4 to 8 quarts for an 
adult. 

On some persons this gas has a highly exhilarating or in- 
toxicating effect, and produces the most agreeable sensations, 
often attended by momentary mental hallucinations, and cor- 
responding actions. On others it produces mental depression, 
and melancholy forebodings. Its action commonly continues 
only for a few moments, and its effects seldom or never pro- 
duce a state of languor or debility, which might be expected 
to follow such a degree of excitement. 

The composition of the protoxide of nitrogen by volume, 
is nitrogen 100, and oxygen 50. 100 cubic inches of this 
gas weighs 46.5 grains, and its specific gravity is therefore 
1.5, air being 1. It is transparent, and colorless, has a sweet- 
ish taste, and an agreeable aromatic smell. It is a supporter 
of combustion, and many sub-stances burn in it with far 
greater energy than in atmospheric air. The burning body 
absorbs the oxygen from the nitrous oxide and thus the nitro- 
gen remains in the vessel. 



Why is it safest to let the gas stand over water awhile before it is breathed 1 After hay- 
ing prepared a bladder, or gas bag, how is this filled with the gas from the jug 7 How is 
the gas respired 7 What is the medium dose for an adult ? What effect is the respira- 
tion of this gas said to produce on the human feelings 7 What is the composition of the 
nl jous oxide 7 What is its specific gravity 7 Does this gas support combustion 7 



NITROGEN AND OXYGEN. 141 

Deuioxide of Nitrogen. — 30. 
_ 1 p. Nitrogen 14+2 p. Oxygen 16. 

Nitric Oxide. Nitrous Gas. 

Deutoxide of nitrogen, as expressed above, and as its name 
•signifies, contains two proportions of oxygen to one of nitro- 
gen. It was formerly called nitric oxide, and nitrous gas, 
but analysis having shown its composition, its name is fixed in 
accordance. This gas is formed by the action of nitric acid 
on copper. Having introduced some copper turnings or 
filings into a retort, pour on them a quantity of strong nitric 
acid or aqua fortis. A violent effervescence will ensue, and 
the gas will escape in abundance. At first it will appear of 
a deep red colour, which is owing to the presence of atmos- 
pheric air in the retort ; but on passing it through water the 
red fumes are absorbed, and the nitrous gas remains pure and 
colorless. 

To understand the chemical changes by which this gas is 
formed, it is necessary to state that nitric acid is composed of 
40 parts of oxygen and 14 parts of nitrogen, and that this 
acid is decomposed by the process. A part of the oxygen of 
the acid unites with the copper, and forms an oxide of the 
metal, while another part of the oxygen continues in union 
with the nitrogen, forming a deutoxide of nitrogen, which, as 
already seen, contains only 16 parts of oxygen. The gaseous 
form of the deutoxide is owing to the absorption of a quantity 
of caloric at the instant of its formation. The evolution of 
this gas is therefore owing to the abstraction of a part of the 
oxygen from nitric acid, by the copper. Other metals, and 
particularly quicksilver, will produce the same effect. 

Nitrous gas, when pure, is sparingl}^ absorbed by water. 
It is a little heavier than atmospheric air, 100 cubic inches 
weighing 31.7 grains, w^hile the same quantity of air weighs 
30.5 grains. It cannot be respired, even in small quantity, 
without a sense of suffocation, and violent coughing. It in- 
stantly extinguishes the flame of most substances, when 
plunged into it, but if charcoal, or phosphorus, in a state of 



What does deutoxide signify 1 What is the composition, and what the equivalent 
numbers for deutoxide of nitrogen 1 WTiat was the former name of this gas 1 How is 
nitric oxide obtained 1 Why do the first portions of this gas appear red *? What are the 
chemical changes by which this gas is formed ? What causes the gaseous form of this 
acid 1 To what Is the evolution of this gas owing 1 What is the weight of this gaa? 
What are its effects on respiration and flame % 



142 NITROGEN AND OXYGEN. 

Vivid combustion, be immersed in it, its oxygen is absorbia 
ana they bum with increased energy. 

When mixed with atmospheric air, red fumes are genera- 
ted, as already noticed. This is owing to the union of the 
oxygen of the atmosphere with the nitrous gas. When pure 
oxygen is added to a portion of this gas, the red becomes still 
deeper, and there is formed nitrous acid, which is entirely ab- 
sorbed by water. Thus these two gases, nitrous gas and oxy- 
gen, are a delicate tes^or each other, the smallest quantity ot 
the one being detected by introducing a quantity of the other. 

From the property of the nitrous gas above stated, it has 
been employed in Audiometry, that is, to ascertain the purity 
of the atmosphere, or the quantity of oxygen it contains. 

The method by which this is done, is to confine a certain 
portion of air in a graduated tube, and then to introduce into 
the tube, a sufficient quantity of the gas to unite with all the 
oxygen it contains. Then as the compound formed between 
the oxygen and the nitrous gas is entirely absorbed by water, 
it is readily seen by the graduated tube w^hat proportion of 
air has disappeared, after agitating the mixture with water, 
and consequently how much oxygen it contained. 

The composition of deutoxide of nitrogen has been accu- 
rately ascertained by burning charcoal in it, which absorbs 
all the oxygen, amounting to exactly one half the volume of 
the whole, and leaves the nitrogen, which amounts to the' 
other half By this analysis, it is found that 100 parts ot 
this gas lose 50 parts of oxygen, and that 50 parts ofnitroger 
remain. 

50 cubic inches of oxygen weigh 16.8 grains, 

50 cubic inches of nitrogen weigh 14.9 grains, 



The 100 parts therefore weigh 31.7 grains. 
The equivalent composition therefore is 

1 atom, or equivalent of nitrogen 14 

2 do. do. oxygen 16 



30 



What acid is formed when this gas combines with an additional portion of oxygen gas 7 
By what fluid is this gas absorbed 7 In what manner is the nitrous gas employed to as- 
certain the quantity of oxygen in the atmosphere ? In what manner has the composition 
of this gas been ascertained 7 What is the composition of this gas '? What is its eqi^ • 
▼alent number 1 What are the equivalent numbers of its elements 1 



NITROGEN AND OXYGEN. 143 

Nitrous Acid — 46. 
1 p. Nitrogen 14+4 p. Oxygen 32. 

The next compound of nitrogen and oxygen wnich we 
^hall notice is nitrous acid. 

This acid is formed by adding oxygen to the compound 
last described, in consequence of which, the nitrogen of that 
compound combines with another portion of oxygen equal to 
that which it before contained. The deutoxide contained 2 
proportionals of oxygen, 16. The nitrous acid contains 4 
proportionals of oxygen, 32. Between these, there is a hy- 
pothetical compound, containing 3 proportions of oxygen, but 
which has not been obtained in a free state. This is called 
hyponitrous acid, and by some subnitrous acid, because it 
contains less oxygen than nitrous acid. 

Nitrous acid may also be obtained by the distillation of 
nitrate of lead, in a retort. (See Nitrate of Lead.) During 
the distillation, the receiver should be kept cold, by surround 
ing it with ice. 

By either of these methods, there is obtained a vapour, or 
gas, of a deep orange red colour, which is the nitric acid in 
a gaseous state. To obtain it pure, it is, however, necessary 
that the receiver should be first exhausted by the air pump, 
because the gas is instantly absorbed by water, and a mercu- 
rial bath cannot be employed, because the gas acts upon that 
metal. 

By volume this acid is composed of. 

Nitrogen 100 By weight, Nitrogen 14 

Oxygen 200 Oxygen 32 



300 ^ 46 

Nitrous acid, in its fuming state, is totally irrespirable ; but 
supports the combustion of phosphorus or charcoal, when 
these are introduced into it in a state of combustion. 

Water absorbs this gas in large quantities, and acquires 
thereby, first a green and afterwards a blue tint. If still 
more be added, it becomes yellow, or colourless, and forms a 
solution of nitrous acid in water. 



WTiat are the processes by which nitrous acid may be obtainedl What is the eompo- 
cition of this acid 7 In what does this acid occur, and what is its colour? How is this 
acid obtained in its pure state 1 Why cannot a mercuiial or water bath be employed to 
confine this gas 1 What are the definite proportions of the elements of this acid by 
volume ana weight 1 Does this gas support combustion or animal life 1 What is laid of 
its absorption by water axwi the colours produced therebfv % 



t44 NITRIC ACID. 

Nitric Acid — 54. 
1 p. Nitrogen 14+5 p. Oxygen 40. 
Aqua Fortis 

If a mixture of oxygen and nitrogen be confined in a glas 
lube containing a little water, and powerful electrical shod 
be passed through this mixture, the water, after a continued 
succession of such shocks, will possess acid properties. Bj 
this process, the two gases are made to combine and for 
nitric acid, which is absorbed by the water. 

This experiment is designed merely to prove tnat the acid 
in question is formed of oxygen and nitrogen. 

The usual mode of forming this acid, is by the distillatioi 
of the nitrate of potash, more commonly called nitre, or salt'\ 
j)etre, with sulphuric acid. The proportions are four parts of] 
nitre, in coarse powder, with three parts of the acid by weight ^ 
The receiver must be large, and kept cold, otherwise much 
of the acid will escape before it is condensed. The strongest 
acid is formed w^hen no water is placed in the receiver, that 
already combined with the sulphuric acid being sufficient to 
condense the nitric acid vapor as it is formed. 

The strongest nitric acid is without color, and has a spe- 
cific gravity of 1.5, that is, this acid is by one half heavier 
than water. In this state it contains 25 per cent, of water. 

The dry nitric acid, which is formed by the condensation 
of its constituent gases, contains no water, and is composed, 
as stated at the head of this section, of 1 proportion of nitro- 
gen, 14, and 5 proportions of oxygen, 40. The combining 
number of the dry acid is, therefore, 54. 

The acid obtained by distillation contains the same ele- 
ments as the dry acid, and in the same proportions, but with 
the addition of two proportions of water. Now, the combi- 
ning proportion of water being 9, that is, oxygen 8 and hy- 
drogen 1, it is easy, by the above data, to find the combining 
or equivalent number for liquid nitric acid. It may be stated 
thus : 



{ What is the composition of nitric acid, and what Us combining number ? What ex 
periment shows that this acid is formed of nitrogen and oxygen 1 What is the usual 
mode of obtaining this acid? In what manner is the strongest nitric acid former U 
Whence comes the water to absorb the acid vapor when none is placed in the receiver 7 
What is the specific gravity of the strongest acid 1 What proportion of water does it 
contain? How is the dry nitric acid formed? Does the acid obtained by dietillation 
contain be same elements as the dxy 1 



NITRIC ACID. 




1 prop, of Nitrogen 
5 prop, of Oxygen 


14 

40 




54 dry acid. 


2 prop, water 


18 




72 liquid acid. 



145 



The acid in this state is called hydro nitric acid, from 
Greek word signifying water, to denote its combination with 
that fluid. When this acid combines with other substances 
it abandons the water, which therefore is not reckoned in its 
equivalent number. In this state it is called anhydrous nitric 
acid, denoting that it contains no water. 

Nitric acid is an exceedingly acrid and corrosive substance. 
It stains the skin and nails of a permanent yellow, and is an 
active poison when swallowed. 

It parts with its oxygen with great facility, and hence is 
decomposed by nearly every combustible body. It combines 
with most of the metals, and decomposes all vegetable and 
animal substances. 

As a proof of the slight degree of force with which this 
acid retains its oxygen, take some warm, dry, and finely pow- 
dered charcoal, and pour on it a few drachms of strong nitric 
acid. The charcoal will be ignited, Avith the emission of im- 
mense volumes of red fumes. By this process the acid is 
decomposed, and parts with 2 or 3 portions of its oxygen to 
the charcoal, in consequence of which it is converted into 
nitrous acid, and deutoxide of nitrogen, which pass off in the 
form of red fumes. 

If an ounce of the spirit of turpentine be placed in a cup, 
and on it there be poured suddenly, about half an ounce of 
this acid, the turpentine will be inflamed with an explosion, 
sending forth a great quantity of black smoke, and often 
throwing the acid and fire to a considerable distance. 

In both these cases, the acid parts with its oxygen with so 



What are tlie constituents of liquid nitric acidl What is the chemical name for tho 
liquid nitric acid? When this acid combines with other substances, what becomes of its 
water 1 What is the chemical name for the dry acid ? What are the properties of nitric 
acid 1 Ho w is it shown that this acid holds its oxygen with a slight force ? What effect 
Joes the action of the charcoal have on this acid? What are the red fumes which pass 
off during this experiment 1 How may spirit of turpentine be inflamed by this acid? 
Why are the combustibles set on fire by this acid % 

13 



146 AMMONIA. 

much freedom, aud the combustibles absorb it with such avi- 
dity, as to set them on fire. 

In making the latter experiment, the vial containing the 
acid should be tied to a long stick, otherwise the operatoi 
will be in danger from the explosion. 

Nitric acid forms a great number and variety of salts, 
when combined with the different metals, earths, and alkalies. 
Most of these sahs scintillate when thrown on burning char- 
coal. This is in consequence of the oxygen which the salt 
emits when exposed to heat, and by which the combustion oi 
the charcoal is rendered more vivid. This scintillation i? 
a sure proof that the salt is a nitrate. 

Ail the nitrates are soluble in water, and many of them 
furnish oxygen gas of more or less purity when heated in a 
retort* 

NITROGEN AND HYDROGEN. 

Ammonia 17. 

1 p. Nitrogen 14+3 p. Hydrogen 3. 

Hartshor7i. 

There is a substance well known to artists, and others, by 
the name of sal-ammoniac. In chemistry its name is muriate 
of ammonia. If some of this substance be pulverized by 
Itself, and then mixed with an equal portion of unslaked 
quicklime, also in powder, and then introduced into a retort, 
upon the application of a gentle heat, there will arise an ex- 
tremely pungent gas, which is ammonia. 

Water absorbs this gas with great avidity, and in large 
quantities, and consequently it cannot be collected like most 
other gases, by means of the water bath. 

In the absence of a mercurial bath, therefore, its proper- 
ties can be examined by receiving it in a bladder attached 
to the retort, or by means of a tall bell glass, and the appa 
ratus described at Fig. 40. This gas is transparent, and co- 
lorless. In its pure state it cannot be respired. An animal 
cannot live in it, and it extinguishes the flame of barning 
bodies. 



What is said of the salts formed by the combinations of nitric acid 7 Wliy do th« saMs 
of this acid scintillate when thrown on burning charcoal ? What is said of the solubility 
of the nitrates'? How is ammonia obtained? Why cannot this gas be collected under 
water ] How may its properties be examined without a mercurial bath 1 



CARBON. 147 

This gas is composed of 

1 equivalent or atom of nitrogen 14 
3 do. do. hydrogen 3 

Its combining weight is therefore 17 

It is much lighter than atmospheric air, 100 cubic inches 
weighing only 18 grains. 

When this gas is absorbed by water, which will take up 
more than 500 times its own bulk of it, there is formed the 
well known pungent liquid called spirit of sal ammoniac, or 
spirit of hartshorn, and by the apothecaries, liquid ammonia. 

When ammoniacal gas is submitted to the pressure of 6 or 
7 atmospheres, equal in the whole to about 100 or 120 pounds 
to the square inch, it is condensed into a clear colorless 
liquid, but when the pressure is removed, it again expands, 
and assumes its former gaseous state. 

Ammonia is called the volatile alkali, by which it is distin- 
guished from the fixed alkalies, soda and potash. It possesses, 
fully, ail the properties of an alkali, having an acrid taste, a 
strong affinity for water, and being capable of neutralizing 
the corrosive qualities of the acids. 

The article used in smelling bottles, and called volatile salts^ 
and salt of hartshorn, is a carbonate of ammonia. 

The salts of ammonia, and particularly the muriate and 
carbonate, are articles of considerable importance in com- 
merce, in the arts, and in medicine. 

Carbon.-^^, 

Nature furnishes carbon in its purest state, in the form ot 
that precious gem, the diamond. 

That the diamond is nothing but pure carbon, is proved by 
direct analysis. If in a glass vessel containing oxygen gas, 
a piece of diamond be placed, and then exposed to the intense 
heat of a large convex lens, or burning glass, the diamond 
entirely disappears, and there remains in the vessel carbonic 
icid, instead of oxygen. Thus the diamond, like other com- 



What are the most obvious properties of ammonia % What is the composition of am 
monia, and what is its equivalent number 7 What is the weight of 100 cubic inches ot 
his gas? How is liquid ammonia formed 7 What quantity of this gas will water ab 
wrb7 Wliat is said of the condensation of ammonia into a liquid 7 What is the article 
-billed volatile salts 7 \^^lat is said of the alkaline properties of ammonia 7 How is U 
jsav&ii t)iat tlie diamond is composed of p^e carbott % 



f48 CARBON, 

bustibles, forms carbonic acid by being burned, or by uniting 
with oxygen. When charcoal, or carbon from wood, is burned 
in pure oxygen gas, exactly the same result is produced, the 
charcoal entirely disappears, and the oxygen is converted into 
carbonic acid. 

Charcoal may be obtained for experiments, by burying 
wood under sand, in a crucible, and exposing it to an intense 
heat for an hour or two. By this process, the water and 
other ingredients of which wood is composed are driven off, 
and the carbon remains. 

Both diamond and charcoal sustain the most intense de- 
grees of heat, without change, provided oxygen is entirely 
excluded from them. Charcoal, when newly prepared, pos- 
sesses the property of absorbing large quantities of air, or 
other gases, at common temperatures, and of yielding the 
greater part of them again when heated. There is, however, 
a great difference in respect to the quantity absorbed, depend- 
ing on the kind of gas with which the experiment is made. 
Ammoniacal gas is taken up in the largest quantit}^ this be- 
ing 90 times the bulk of the charcoal. Muriatic acid gas is 
absorbed in the proportion of 85 times the bulk of the char- 
coal. Other gases are absorbed only in small proportions, 
nitrogen being only 7i times, and hydrogen 1.75 times the 
bulk of the charcoal. The greatest absorption takes place in 
charcoal made from the most compact kinds of wood, and the 
amount is much diminished when the charcoal is reduced to 
powder. Charcoal, recently prepared, has the property of re- 
sisting putrefaction in animal substances, and of rendering 
such substances sweet, after they are tainted. The most offen- 
sive stagnant water, loses its odor and becomes perfectly 
sweet by being filtered through powdered charcoal. 

It also destroys the color of many substances. Vinegar 
loses its color, and becomes transparent like water, by being 
boiled with charcoal, and red wines, or colored brandy, are 
bleached by passing through it. The best charcoal for these 



, When diamond, or charcoal, is burned in oxygen gas, what is the product 1 How may 
charcoal be obtained from wood in a pure state 1 What peculiar property does newly 
prepared charcoal possess 1 What difference is there in respect to the quantity of the 
different gases absorbed by charcoal 1 What gases are absorbed in the greatest, and whar 
in the least quantity 1 What effect docs newly prepared charcoal have on putrefying 
animal substances ? What effect does charcoal have on the color of particular subetap 
cea 1 What kind of charcoal is best for the above purposes 1 



Cj\ilBON AND 0XY<3fiN. 149 

purposes is prepared by calcining animal substances in close 
vessels. 

In the present state of knowledge, charcoal is a simple sub- 
stance, having resisted all attempts to decompose, or separate 
it into other elements. Its atomic weio^ht or combining num- 
oer is 6, this being the proportion in which it is found to unite 
with oxygen, to form carbonic acid, and in no instance has it 
been detected in a less proportion in combination* 



CARBOT^ ANl) OXYGEN. 

Carbonic Acid — 22. 

1 p. Carbon 6+2 p. Oxygen 16^. 

Fixed Air, 

It has just been stated, that when diamond or charcoal is 
Durned m oxygen, the latter is chariged into carbonic acid. 
By this process the volume of oxygen is not changed, but its 
weight is increased by exactly the amount of the diamond, or 
charcoal, consumed. Carbonic acid, therefore, consists of 
oxygen, with a quantity of charcoal dissolved in, or combined 
vviih it. 

This acid can, however, be obtained by a much cheaper, 
and more direct method, than by the combustion of diamond, 
or even of charcoal, in oxygen gas. 

Carbonic acid exists in a fixed state, in vast abundance, as 
a part of the composition of limestone or marble. This che- 
mical compound, so abundant in nature as to form immense 
mountains, is composed of 22 parts of carbonic acid, and 28 
of lime. 

Carbonic acid may therefore be obtained most readily, by 
exposing carbonate of lime to the action of some acid which 
has a stronger affinity to the lime than the acid has with 
which it is naturally combined, and thus by forming a new 
compound between the lime and the stronger acid, the car- 
bonic acid will be set at liberty. 



Is charcoal a simple, or a compound body 7 What is the combining number, or 
utomic weight, of carbon ? When diamond, or charcoal, is burned in a confined portion 
)f oxygen gas, what effect does the combustion have on the volume and weight of the 
gas 1 In what natural compound is carbonic acid contained in great abundance 1 What 
proportion of carbonic acid does marble contain ? What are the chemical principles on 
Which carbonic acid may be obtained from limestone, or marble 1 

13* 



150 



CARBON AND OXYGEN, 

Fig, 5S, 




For this pur 
pose, introduce 
pure white mar 
ble, in small frag- 
ments, into the 
two necked bot- 
tler, ^g. 58. hav- 
ing the bent tube 
c, connected with 
one of the necks 
and passing un- 
der the jar d, fill- 
ed with water 
and inverted in 
the water bath. 
-Then pour 

through the funnel Z>, some sulphuric acid, diluted with fiyej 
or six parts of water. Effervescence Avill immediately en- 
sue, in consequence of the escape of the gas, which in a few 
minutes will be seen to rise in bubbles through the water in 
the jar. 

The chemical changes during this process illustrate th^ 
law of simple affinity, formerly explained, viz., that one sub- 
stance may have an attraction for several others, but with dif- 
ferent degrees of force. Thus lime has an affinity for carbo- 
nic acid, with which it combines and forms carbonate of lime. 
But sulphuric acid having a still stronger attraction for the 
lime, when this is added, the carbonate is decomposed, the 
sulphuric acid and lime unite and form sulphate of lime, while 
the carbonic acid being thus rejected, escapes in the form oi 
gas. 

This gas is inodorous, colourless, and elastic. It extin- 
guishes burning substances of all kinds, and is so poisonous, 
that a small quantity of it mixed with atmospheric air destroys 
animal life. 

It is this gas which destroys the lives of many persons everj 
winter, in consequence of Avarming close rooms with open 
vessels of burning charcoal. In such cases the air becomes 



Explain Fig. 58, and describe the process of obtaining carbonic acid gas from marbla 
Explain how this process illustrates the law of simple affinity. What new salt is formed 
when sulphuric acid is poured on marble ? What is the effect of this gas on flame, and 
animal life 7 When ch ircoal is burned in an open vessel, in a close room, what is th< 
effect oa the air of the room 1 



CARBON AND OXYGEN. 151 

torn two causes ; the charcoal, by abstracting the 
bxygerffrom the atmosphere, would leave only the nitrogen, 
which, as we have already seen, will not support animal life, 
^'he mere absence of the oxygen would, therefore, be the ne- 
gativ^e means of destroying life. But this is not the most ac- 
tive cause of destruction. The air is not only deprived of its 
oxygen, by the burning charcoal, but the oxygen, by uniting 
with the charcoal, becomes an absolute poison ; this is indeed 
of so deleterious a nature, that when pure, it causes death by 
producing a spasm of the glottis, thus closing entirely the 
passage to the lungs, and when mixed with atmospheric air, 
in such a proportion as to be taken into the lungs, it then 
acts as a narcotic poison, producing dimness of sight, loss of 
strength, difficulty of breathing, then entire suspension of 
respiration, and finally, insensibility, apoplex}^ and death. 

When limestone is exposed to heat, this gas is driven off^ 
and in consequence of this loss, the limestone is converted 
into quicklime, a substance well known as the basis of mor- 
tar for building. The gas, thus extricated, being quite pure, 
is exceedingly deleterious, and sometimes proves fatal to the 
workmen and others in the vicinity of the kiln, where the 
burning is performed^ 

M. Foder states7T5iat in the year 1806, a family residing 
at Marseilles, consisting of seven persons, were all rendered 
apoplectic, in consequence of breathing carbonic acid, which 
was extricated from an oven in the yard of the house, where 
limestone was burning. The gas had come into the house 
through the door and windows, and by some means it was 
found, during the night, that the family were in danger, and 
the alarm was given, but not in time for any one to escape. 
In the morning all the seven were found in different places, 
one on the stairs, one on the step of the door, &c., with 
lamps in their hands, in the attitude of flight; but the dele- 
terious gas had taken away their strength, and put out their 
lights. They all appeared to have fallen down of apoplexy, 
while attempting to escape death by flight. Five were dead 
beyond recovery, but the tw^o others were brought to life. 

Some people, who are perfectly aware of the poisonous 



How does pure carbonic acid cause death 1 When mixed with air, so as to be respired, 

how does it cause death 1 When limestone is exposed to a red heat, what changes are 

produced on it 1 What were the circumstances under which a family at Marseilles were 

rendered apoplectic by this gas 1 Is there any difference between the poisonous effects o? 

tarcoal prepared in a coal-pit, and that taken from the liearth 1 



t52 CAHBON AND OXYGEN^ 

effects of the air arising from ignited charcoal, which has 
been prepared in coal-pits, still unaccountably believe, that 
the coals from a common fire are innocent. This opinion 
has probably arisen from the circumstance, that coals from 
the fire are taken up with a quantity of ashes, in which they 
are chiefly covered, so that their combustion is made less 
rapid, than when charcoal alone is used. But that there is 
no difference in respect to the poisonous property of this gas, 
whether the charcoal has been prepared in a coal pit, or on 
the hearth, is proved by the fact, that a respectable citizen 
and his wife, a short time since, had nearly fallen victims to 
this mistaken opinion. 

Water absorbs carbonic acid from the atmosphere, and it 
is owing to its presence in spring and well water, that we are 
indebted to their pleasant flavour. Boiling causes this gas to 
escape in consequence of the heat^ and whoever has tasted of 
water immediately from a fountain, and of another portion 
of the same water, which has been boiled, will observe a re* 
markable difference. Water which has been recently boiled, 
will absorb its own bulk of carbonic acid, when agitated with 
it. The smart and agreeable taste peculiar to soda water, 
to lively beer, champaigne, cider, and porter, is owing to the 
presence of this gas. This shows that, though a deadly 
poison when taken into the lungs, it may be taken into the 
stomach, not only with impunity, but with pleasure. 

The poisonous quality of this gas is a striking instance ol 
the change produced on bodies by chemical combination. 
Charcoal alone is so inert as to be taken into the stomach in 
any quantity, without other deleterious effects, than what 
might arise from over distention, and in fine powder it is so 
far from being injurious to the lungs, that the coalmen consi- 
der their business as of the most healthy kind. Oxygen, as 
it exists in the atmosphere, is the very pabulum of animal life, 
and when perfectly pure, may be respired without any other 
ill effects, except what arise from over excitement. But when 
these two substances are chemically united, they form, as 
already described, a compound of the most deleterious kind, 



What is said of the absorption of this gas by water, and the lively taste given the fluid 
m consequence 1 Why does water which has been boiled taste flat and insipid 7 To 
what liquids does this gas give their smart and lively taste 1 What does this prove in 
respect to the poisonous quality of thrs gas 7 How do the poisonous qualities of this gaif 
Illustrate the changes produced on bodies by chemical combinations 1 



CARBON AND OXYGEN. 153 

a poison which, according to M. Halle, destroys animal life 
in the space of tAvo minutes. 

The specific gravity of this gas is 1.52, air being 1 ; so 
that it is about one half heavier than air. It may be poured 
from one vessel to another like water, and as it instantly ex- 
tinguishes flame, lights may be put out with it, in a manner 
which will puzzle and astonish those who are not in the se- 
cret. If a short piece of candle be lighted and set in a tum- 
bler, and then a jar of this gas, which in appearance contains 
nothing, be held so that its contents run into the tumbler, the 
light will be as efTectually extinguished, as though the tum- 
bler had been filled with so much water. 

One of the best tests of the presence of this acid is lime 
water, which though perfectly transparent before, instantly 
becomes cloudy, or turbid, when the smallest quantity of this 
gas is blown into it. The small quantity of carbonic acid 
which is generated in the lungs at every inspiration, is suf- 
ficient to form a precipitate in lime water. (See Respira- 
tion.) 

The cause which renders lime water turbid by being mixed 
with carbonic acid is easily understood. Water dissolves a 
small quantity of lime which it holds in solution ; but carbo- 
nate of lime is insoluble in water. When carbonic acid is 
blown into a vessel of lime water, the lime instantly combines 
with it, forming a carbonate of lime, which, being insoluble, 
is seen in the form of a white cloud. The carbonate thus 
formed, being heavier than water, sinks to the bottom, or is 
precipitated. 

The large quantities of this acid which are formed by com- 
bustion and respiration, it might be supposed, would increase 
the quantity in the atmosphere, particularly in crowded ma- 
nufacturing cities, so as to make the air poisonous. But as 
already explained, the wisdom of Omnipotence has prevented 
the accumulation of this gas in particular places, in conse- 
quence of its specific gravity, for experiment shows, that not- 
withstanding the great difference existing among the gases 
111 this respect, they all mix uniformly. Hence, by this won- 
derful provision, or exception to the general law of gravity, 



What is the specific gravity of this gas? How may lights be extinguished by this gas 
in a manner to puzzle those who are not in the secret? What is a good test for carbonic 
acid 1 What effect is apparent when a little of this gas is blown into lime water? Why 
doc^ lime water become turbid by the presence of carbonic acid? Why is the atmos- 
phere seldom rendered poisonous by the accumulation of this gas? 



154 suLPHrR. 

this gas, though extricated m immense volumes in the free 
open air, soon diffuses itself on all sides, and mixes with the 
surrounding atmosphere, so as seldom to prove deleterious by 
local accumulation. 

The composition of this gas has been determined w^ith ac 
curacy, and as seen at the head of this section, it is composec 
of 2 proportions of oxygen 16, and 1 proportion of carbon 6; 
hence its combining weight is 22. ^ 

Carbonic Oxide. — 14. 
1 p. Carbon 6+1 P- Oxygen 8. 

When two parts of chalk, and one of iron filings, are mixed 
together and heated in a gun-barrel, carbonic oxide gas is 
obtained. 

The student will readily understand the principle of its 
formation. An oxide contains too small a proportion of oxy- 
gen to form an acid. When lime or chalk is heated, carbonic 
acid is extricated, and when iron is heated, it has a strong 
attraction for oxygen. When therefore the chalk and iron 
filings are heated together, we may suppose, in the first place, 
that the carbonic acid is extricated, as usual, but that the iron 
instantly absorbs one half of its oxygen, thus converting the 
acid gas into an oxide. 

This gas possesses the mechanical properties, color, and 
transparency of carbonic acid. Like that gas, it extinguishes 
the flame of burning bodies, but is itself inflammable, the 
light which it puts out, setting it on fire at the surface, where 
it burns quietly, with a pale, lambent flame. The combining 
proportion of carbon has been determined from this com- 
pound, its elements, carbon and oxygen, having never been 
found to combine in smaller proportions than 6 of carbon and 
8 of oxygen by weight. 

SULPHUR 16. 

Sulphur is found in the vicinity of volcanoes in large quan- 
tities, being sublimed, or brought up from the depths below, by 
the heat of the volcano, where it existed in combination with 
the metals. It is also found combined with various metals, 

What is the composition of this gas, and what its combining number ? How is carbo- 
nic oxide formed 1 What are the chemical changes which take place in forming this gas 
by means of chalk and iron filings? What are the properties of this gas? What is its 
composition and combining number ? In what situation is sulphur chiefly found 1 
Whence comes the sulphur found in the vicinity of volcanoes 1 



8ULPHUR AND OXYGEN. 155 

forming" sulphurets, a class of compounds hereafter to be ex- 
amined ; nor is it entirely wanting in the animal and vegeta- 
ble kingdoms, many substances in each containing it in small 
quantities. 

Sulphur is a well known brittle solid, of a greenish yellow 
color, which has little or no taste, but which emit.s a peculiar 
odour when heated, or rubbed. 

Its specific gravity is nearly 2, water being 1. When 
heated to a temperature a little above boiling water, it melts, 
and becomes completely fluid. In this state it is cast into 
moulds, and is known in commerce under the name of roll 
brimstone. If the heat is raised to 300°, it loses its fluidity, 
becomes viscid, and acquires a reddish color. If in this 
state it be poured into water, it becomes ductile, and is then 
employed to take the impressions of medals and seals. 
The color and texture of these false medals have the appear- 
ance of some metallic alloy, and those who are unacquaint- 
ed with their composition, taking them for such, are at first 
surprised at their lightness. 

When sulphur is heated to 500° in a close vessel, it rises 
in vapor, or suhlimes, and is condensed unchanged, except in 
form, which is that of an impalpable powder, well known 
under the name of flowers of sulj)hur. In this manner it 
is purified. 

Sulphur combines with the earths, alkalies, the metals, and 
w4th several proportions of oxygen. Its compounds are there- 
fore numerous, and some of them interesting. It has not 
been found combined with any substance in a less proportion 
than 16, v/ith which it forms an acid, called the hyposulphur- 
ous, when united to 8 parts of oxygen. 

Sulphur, so far as known, is a simple body ; all attempts 
io decompose it, having proved fruitless. 

SULPHUR AND OXYGEN. 

Sulphurous Acid — 32. 
1 p. Sulphur 16+2. p. Oxygen 16. 
When sulphur is burned in pure oxygen gas, the latter 



(low is sulphur described ? What is its specific gravity 1 At what degree of heat 
tees sulphur melt 7 What is roll brimstone ? How is sulphur prepared to take the im- 
pressions of medals and seals 1 How are flowers of sulphur prepared 1 With what 
Wher bodies does sulphur combine 7 What is the lowest proix)rtion in which sulphur is 
iiiown to combine 7 Is it an eiement or a compound 7 



156 SULPHUR AND OXYGEN. 

suffers no change of volume, but acquires a most suffocating 
and pungent odour, and many new properties, entirely differ- 
ent from those of oxygen. The compound so formed is sul- 
'phurous acid gas. It is colourless and transparent ; extin- 
guishes flame and animal life ; and first turns vegetable blue 
colours to a red, and then destroys them. When diluted with 
a large proportion of atmospheric air, it is still so acrid as to 
produce a sense of suffocation and violent coughing on those 
who attempt to breathe it. 

It is the same gas which is formed when sulphur is burned 
in the open air, but when burned with oxygen it is pure and 
undiluted. It possesses the property of bleaching linen, silk, 
straw, &c., and hence is employed by milliners and others 
for this purpose. 

Its specific gravity is more than double that of atm.ospheric 
air, and hence it may be kept for some time in jars by mere- 
ly covering them with a piece of glass. Its equivalent com- 
position is 16 sulphur and 16 oxygen. Its bleaching proper- 
ty may be shown, by introducing a red rose, or other coloured 
flower, into a jar containing it, which will soon becom.e white. 
The rose must first be moistened, otherwise the experiment 
will not succeed. The colour may again be restored by an 
alkali. This gas has a strong disposition to unite wdth anothe] 
proportion of oxygen, and hence it will revive some metallic 
oxides, by depriving them of their oxygen. 

This property may be used as the means of making an 
interesting experiment. 

Make a solution of acetate (sugar) of lead in pure water, 
and with it moisten a piece of ribbon, or a small plant, such 
as a sprig of mint. The thing moistened of course presents 
no other appearance than if wet with common water, but when 
plunged for a moment into ajar of this gas, it comes out com- 
pletely covered Avith a coat of brilliant metallic lead. 

This chemical change is thus explained. The acetate of 
lead is an oxide of the metal, dissolved in the acetic acid, or 
vinegar. The sulphurous acid having a stronger attraction 



How is sulphurous acid gas produced 7 What effect does this gas produce on flame, 
animal life, and vegetable colors 7 How does this gas differ from that produced by 
burning sulphur in the air 7 What is the specific gravity of this gas 7 What is its equi- 
valent composition 7 How may the bleaching property of this gas be shown 7 How may 
the color of the rose again be restored 7 How may a ribbon, or small plant, be covered 
with metallic lead by means of this gas 7 What are the chemical changes wiiich lake 
lace in reviving the lead by this acid 7 



SULPHUR AND OXYGEN. 157 

for oxygei. than the lead has, the acetate is decomposed by 
being deprived of its oxygen by the acid, and is thus revivea, 
or brought to its metallic state. 

According to Mr. Faraday, the sulphurous acid is conden- 
sed and brought into the liquid state, by being submitted to 
the pressure of two atmospheres, which is equal to that of 30 
pounds to the square inch. 

This acid unites with metallic oxides, and forms salts, called 
sulfhite^. 

Sulphuric Acid — 40. 

1 p. Sulphur 16+3 p. Oxygen 24. 

Oil of Vitriol. 

Sulphuric acid is an article of considerable consequence in 
commerce and the arts, and is prepared in large quantities in 
Europe and America. 

It was formerly obtained by the distillation of a well known 
substance called green vitriol or copperas, and waa therefore 
called oil of vitriol. The composition of this acia^s above 
seen, gives it the name of sulphuric acid ; and green vitriol, 
therefore, which is composed of this acid and iron, is the 
sulphate of iron. 

By distilling this substance at a high heat, it is decomposed, 
and the acid is obtained in the form of a dense, colorless, 
liquid, of an oily appearance, which emits copious white 
fumes in the air. If this liquid be again distilled at a lower 
degree of heat, into a receiver surrounded with ice, there will 
pass over a colorless vapor, which will condense in the re- 
ceiver, in the form of a white crystalline solid. This solid 
is dry, or anhydrous sulphuric acid, so called, because it con- 
tains no water. 

The sulphuric acid of commerce, is this solid dissolved in 
water. This acid is prepared by the combustion of 8 parts 
of sulphur mixed with 1 part of nitre, in large chambers lined 
with sheet lead. The acid is formed in the state of gas, 
and is absorbed by a thin stratum of water placed on the floor 
of the chamber. The following is the theory of this pro- 



How may this acid be condensed to a liquid state? What are the salts called which 
this acid forms with metallic oxides 7 How was sulphuric acid formerly obtained ? What 
13 the chemical name of copperas? How is the dry, or anhydrous sulphuric acid pro- 
cured 7 Of what does the liquid sulphuric acid of commerce consist? Describe the 
manner in whicli the siilj^huric acid of commerce is prepared. 

4 



58 SULPHUR AND OXYGEN. 

cess. The sulphurous acid, formed by the buri "^2; sulphu*? 
takes a portion of oxygen from the nitre, and ib convert8(^ 
into sulphuric acid. This acid then combines with the potasb 
of the nitre, and displaces nitrous and nitric acids in vapor 
These vapors are decomposed by the sulphurous acid into 
nitrous gas, or deutoxide of nitrogen. This gas, suddenly 
expanded by the heat, rises to the roof of the chamber, where 
there is an aperture communicating with the open air. 
There it absorbs a portion of oxygen from the atmosphere 
and is converted into nitrous acid vapor, which, being a heavy 
aeriform body, immediately falls down upon the sulphurous 
flame, and imparting a portion of its oxygen to the sulphur- 
ous acid vapor, converts it into sulphuric acid, which is then 
absorbed by the water. The nitrous acid vapor, being thus 
reconverted into nitrous gas, again ascends to the roof of the 
chamber for another dose of oxygen, with which it descends 
*as before, and thus the process continues. 100 parts of ni- 
tre, and 800 of sulphur, will produce 2000 parts of the 
acid. 

From Dr. Ures' paper on this subject, we learn that the 
common acid of the shops contains from 3 to 4 per cent, of 
foreign matter, consisting chiefly of sulphate of potash, and 
sulphate of lead, and that it often contains much more than 
these proportions, inconsequence of the introduction of nitre, 
to remove the brown color, accidentally given the acid by bits 
of wood, or straw. 

The purest sulphuric acid obtained by the usual process 
has a specific gravity of about 1845, water being 1000. If 
it is much heavier than this, adulteration by means of some 
ponderous substance may be suspected, and if much lighter, 
its strength will probably be found deficient in consequence 
of dilution with water. In consequence of the strong attrac- 
tion of this acid for water, with which it unites in all propor- 
tions, it absorbs moisture from the air with avidity, and thus 
when vessels containing it are left open, they gain in weight, 
instead of losing by evaporation. If carboys of this acid are 
permitted to stand in a damp place, as in a cellar, with the 
stoppers left out, there will probably be a gain in weight, 



What impurities does the sulphuric acid of commerce always contain? What pro- 
portion of these substances does the common sulphuric acid of the shops contain '? How 
may the quantity of foreign matter in this acid be ascertained 1 What is the specific 
gravity of the best sulphuric acid, obtained by the usual process 1 Wliat is said of the 
absorption of water by this acid, when left open 1 



SULPHUR AND OXYGEN. 159 

which will amount to much more than the interest of the 
m^j0(fy the acid cost. It therefore becomes honest dealers, 
as well as careful buyers, to see that this acid is well secured 
from contact with the air. 

This acid is one of the most caustic and corrosive of all 
substances. When mixed in the proportion of four parts of 
acid with one of water, the temperature of the mixture rises 
to 300°. Its extreme activity as a caustic seems to depend 
on its avidity for moisture, and the heat occasioned by the 
union. On the entire skin, when this is dry, it produces no 
immediate eifect, but if there is the smallest erosion or 
scratch, it operates on that part instantly, and with the most 
intense and painful energy. The flesh appears to be first- 
burned, and then dissolved by its action. 

In case of any accident, where the concentrated acid is 
thrown upon the clothes or skin, as it is generally known that 
this' acid burns, the spectators run for water, which is thrown 
on, with the intention of diluting the acid, and thus to prevent 
Its farther action. This, though meant in kindness to the 
sufferer, might be the means of his destruction ; for the de- 
gree of heat, thus raised, would be sufficient to destroy his 
skin, without the farther action of the acid. In such cases, 
there is much less danger in waiting until some potash, chalk, 
or even ashes, can be procured, and thrown on the part. 
Meantime, the sufferer should be stripped of the clothing on 
which the acid has fallen, and the acid absorbed from the skin 
with a moistened sponge, or cloth, or even a handful of dry- 
clay, thrown upon the part. 

Strong sulphuric acid boils at 620°, and freezes at 15° be- 
low zero. 

The dry acid is composed of 

1 equivalent of sulphur 16 
3 do of oxygen 24 

40 

The common or hydro-sulphuric acid contains, in addition 



In what proportions does a mixture of this acid and water produce the greatest degree 
of heat 7 On what does the causticity of this acid seem to depend 1 In case this acid is 
accidentally thrown upon a person, what is said to be the best method of neutralizing its 
efiao^s 1 What is the composition of the dry acid 1 What quantity of water does the 
strongest common acid contain 7 What is the equivalent number for the hydrosulphu* 
nc acid ] 



160 PHOSPHORUS. 

to the above, one proportion of water, making i. equivalent 
number 49. 

*«.,,^ PHOSPHORUS — 12. 

Phosphorus is a yellowish, inflammable solid, which in 
the open air emits white fumes, and at common temperatures 
is luminous in the dark. 

This substance has never been found in a simple state, but 
is combined with animal substances, in considerable quanti- 
ties, and is occasionally found in minerals. 

It is obtained from bones by the following process. Iv 
the first place, the bones are calcined, or burned in an oper 
fire, and then pulverized, and digested for two or three days, 
with half their weight of sulphuric acid, to which water ii 
occasionally added. This solution is then mixed with twice 
its bulk of hot water, and the liquid separated by straining 
through a cloth. By this process, the bones, which are com- 
posed of phosphoric acid and lime, are decomposed, and two 
nev/ salts, viz., the sulphate of lime, and the diphosphate of 
lime, are formed. The sulphate of lime is insoluble in water, 
and therefore the filtrated solution contains only the biphos- 
phate, which is soluble. Thus, the bones, which are a phos- 
phate of lime, mixed with animal matter, are first deprived 
of this matter by burning, and then converted, in part, int® 
the biphosphate by the sulphuric acid. We have, then, in 
this stage of the process, a solution of the biphosphate, or 
acidulous phc-phate of lime in water. This solution is then 
evaporated to :he thickness of* syrup, mixed with one fourth 
of its weight of charcoal in powder, and distilled with a strong 
heat, in an earthen retort. The charcoal combines with the 
oxygen of the biphosphate, which being thus decomposed, 
the phosphorus distils over, and is obtained in a vessel of 
water, into which the mouth of the retort is placed. 

Phosphorus, thus obtained, is of a yellowish, or flesh color, 
but may be made colorless and transparent by re-distillation. 

This substance is exceedingly inflammable, so that at 
common temperatures, it is necessary to preserve it under 
water, in well stopped bottles. It may be set on fire by 
slight friction, or even by the heat of the hand. It is in- 



What is phosphorus 'i In what state is phosphorus found, in a simple or combmea 
etate 1 B3 what progress is phosphorus obtained 7 Describe the different chemicai 
changes which take place in the process of its preparation. Wliat is said of the inflam 
raability of phosphorus 1 In what manner must it be preserved from the air 1 



PHOSPHORtS AND OXYGEN. 151 

soxuble in water, but is soluble in either or oils, to which it 
communicates the property of shining in the dark. 

Put a piece of phosphorus into a vial half filled with olive 
oil, then keeping the thumb on the mouth of the vial, warm 
the bottof 1, shaking it now and then, until the phosphorus is 
melted. This forms liquid phosphorus, and a vial thus pre- 
pared, may be occasionally useful to show the hour of the 
night by a watch. All that is necessary for this purpose is 
to hold the vial in the hand for a few minutes, until it becomes 
warm, then take out the cork, and the union of the oxygen 
of the air with the phosphorus, will evolve sufficient light to 
see the hour. 

That the light is owing to the combination of oxygen with 
the phosphorus, or to its slow combustion, in the above in- 
stance, is proved by the fact, that phosphorus may be melted, 
and sublimed in pure nitrogen, w^ithout the least appearance 
of light. Its combustion in oxygen gas is exceedingly vivid, 
and affords a striking and splendid experiment for a public 
lecture room. 

When taken into the stomach, phosphorus proves a viru- 
lent aud deadly poison, though in minute doses, it has been 
used as a medicine, w^hen dissolved in ether. 

PHOSPHORUS AND OXYGEN. 

Phosphoric Acid — 28. 
1 p. Phosphorus 12+2 p. Oxygen 16. 

Phosphorus, as above stated, unites with oxygen with great 
lapidity, and affords an instance of intense chemical action, 
attended w^ith the most brilliant phenomena. During this 
combustion, copious white vapors are produced, which fall to 
the bottom of the vessel in w^hich the experiment is made, 
like flakes of snow. This white vapour is the dry, or anhy- 
drous phosphoric acid. If exposed to the air, it soon attracts 
moisture in sufficient quantity to dissolve it, and thus becomes 
liquid phosphoric acid. 



How is liquid phosphorus prepared 1 For what purpose may a vial of this mixture be 
useful ) How is it proved that the luminous appearance of phosphorus is owing to the 
absorption of oxygen 1 What is said of the poisonous quality of this gas when taken into 
the stomach 7 What is said of the union of phosphorus and oxygen 7 In what form does 
the dry phosphoric acid appear 7 Why does this acid become liquid on exposure to the 
' oir t By T\'hat other method may this acid be formed 7 

14* 



162 PHOSPHORUS AND OXYGEN ^ 

This acid may also be formed by the action u J nitric acid 
on phosphorus. The union is made by dropping pieces of 
phosphorus into the strong acid. The phosphorus absorbs 
one proportion of oxygen from the acid, thus converting this 
acid into the deutoxide of nitrogen, or nitrous gas, which es- 
capes in immense volumes during the process. The phos- 
phorus is thus converted into phosphoric acid, which is ob- 
tained in the solid form by evaporating the solution to dry- 
ness. 

Phosphoric acid unites with water in all proportions, and 
produces a small degree of heat during the solution. Its taste 
is mtensely sour, but it is not corrosive. When heated in 
contact with charcoal, the latter absorbs its oxygen, and the 
phosphoric acid is converted into phosphorus. 

This acid combines with various bases, and forms a clas3 
of compounds called phosphates. Its composition is 

1 proportion of phosphorus 12 

2 do. of oxygen 16 



Consequently its equivalent is 28 
Phosphorous Acid — 20. 
1 p. Phosphorus 12+1 p. Oxygen 8. 

This acid is obtained by exposing pieces of phosphorus to 
.he open air, in consequence of which it spontaneously ab 
sorbs oxygen, and undergoes a slow combustion. 

If tAVO or three sticks of phosphorus be thus exposed in a 
glass funnel, set into the mouth of an empty bottle, the acid 
will be formed, and by attracting moisture from the air, will 
be dissolved, and pass down into the bottle, where at first may 
be found a quantity of liquid phosphorous acid. This acid 
combines with different bases, and forms salts which are 
called phosphites. Phosphorous acid, when exposed for some 
time to the air, absorbs another proportion of oxygen, and is 
then converted into phosphoric acid. Indeed the acid form- 
ed by this method, is probably always mixed with the phos^ 
phoric acid. 

There are several other compounds of phosphorus and 
oxygen, but these are the most important. The phosphate& 
will be described in their proper place. 



When phosphorus is thrown into nitric acid, what are the chemical changes which 
ensue 7 In what manner does charcoal convert phosphoric acid into phosphorus ? Whai 
;S the composition and what the combining number of this acid 1 How is phosphorous 
cid obtained 7 Wiiat are the salts called which this acid forms with the different buses 1 f 



-/ 



BOROK. 163 



BORON 8. 



There is a solid substance, resembling alum in appearance, 
which is used in medicine and the arts, under the name of 
borax. ? rom borax there is extracted an acid, called the 
boracic acid. When boracic acid is heated in contact with 
the metal called potassium, the metal, having a strong affinity 
for oxygen, deprives the acid of that prmciple, and thus its 
base, called boron, is set free. This, so far as is known, is 
an element. B^ron is insoluble in water, alcohol, or oil. It 
may be exposed to the strongest heat iu a close vessel, with- 
out change, but when heated to about 600° in the open air, 
it takes fire, burns vividly, and by the abs5rption of oxygen, 
:s again converted into boracic acid. _ 

Boracic Acid.~Th.is is the only known compound of boron 
and oxygen. It is a natural product, occasionally found in 
springs, and also in several salts, of which borax, or the bo" 
rate of soda is the principal. 

The acid may be obt^ijied from the borate of soda, by dis- 
solving that substance in hot water, and then adding sulphuric 
acid\intil the solution becomes sour. Sulphuric acid com- 
bines with the soda, forming sulphate of soda, or Glauber's 
salt, while the boracic acid thus^ set free, is formed when the 
water cools, in small crystais. It is not readily soluble in 
water, but alcohol dissolves it freely, >vhich being set on fire, 
burns with a beautiful green flame. This green flame is a 
good test of the presence of boracic acid in any composition. 

This acid is composed of 

Boron 1 proportion 8 
Oxygen 2 do. 16 



The combining p. of this acid is therefore 24 

CHLORINE- — 36. 

Oxymuriatic Acid, 4 

This highly important and useful gas is obtained by the 
action of muriatic acid on black, or peroxide of manganese. 
Tlfe most convenient mode of preparing it is by mixing strong 

How is boron obtained % Is boron a compound, or an elementary body i What are 
*he properties of boron 1 What is boracic acid? How may boracic acid be obtained! 
What is the common name for borate of soda? What is the best test for the presence of 
boracic acid 1 Wliat are the elements of boracic acid, and what is its combining num- 
ber 1 How is chlorine obtained? 



4 



164 CMtORlNfi. 

muriatic acid, contained in a retort, with half its weight of 
the black oxide of manganese in fine powder, and then ap- 
plying a gentle heat. The gas may be received in glass bot- 
tles filled with w^ater, and inverted in the pneumatic cistern, 
in the usual way. The water should be warmed, to prevent 
absorption. 

A cheaper mode of obtaining this gas, is to mix three parts 
of sea-salt, powdered with one of the nianganese, in a tubu- 
lated retort, (Fig. 33,) and then to pour in two parts of sul- 
phuric acid, diluted with an equal quantity of water. By the 
heat of a lamp, the gas will be extricated in abundance. 

This gas is of a yellowish green color, the name, chlorine, 
in Greek, signifying green. It has an astringent taste, and 
is so exceedingly suffocating, that a bubble or two let loose 
in a room, will excite coughing and a sense of strangulation. 
Cold water, recently boiled, w411 absorb twice its volume ol 
chlorine, which it gives out again on being heated. 

The specific gravity of this gas is 2.5, so that it is more 
than twice- as heavy as atmospheric air. . 100 cubic inches 
weigh 76.25 grains, while the same quantity of common air 
weighs only 30.5 grains. 

Chlorine was formerly called oxyviuri(itic_ acid,^ from the 
opinion that it was composed of muriatic acid and oxygen. 
But according to thfe logic of chemistry, it is now universally 
considered a simple body, having' never been decomposed, 
though repeatedly submitted to the most active decomposing 
agents known to chemists. Sijr H- Davy submitted it to the 
most powerful effects of galvanism, and to charcoal heated to 
whiteness, without decomposition, and Vv^lthout separating the 
least trac^ of oxygen from it. Hence, according to the pre- 
sent state of knowledge, it is an elementary body. 

Chlorine ' is a supporter of combustion. When a lighted 
taper is plunged into this gas, it burns with a small red flame, 
emitting a large quantity of smoke. Phosphorus takes fire 
in it spontaneously, and so do several of the metals. 

Ftll a, deep, bottle, .05 large tube, with this gas, and set it 
upright, with the mouth covered by a plate of glass. Have 
some antimony prepared, by being pounded in a mortar; 

What are the two processes, described, of obtaining it 1 What is said of the co- 
lor and suffocating effects of this gas 7 What is its specific gravity ? What was 
the former name of this gas 1 Does this gas contain any oxygi?n ? >Vhat is said of the 
experiments of Sir II. Davy on chlorine ? Is this an elementary, or a compound body 1 
Is chlorine a supporter of combustion 1 What substaiices take fire in this gas spontano- 
0USI7 1 



CHLORINE AND HYDROGEN. 165 

then Slide off the cover and pour in the metal. It will taice 
fire before it reaches the bottom, and afford a beautiful show- 
er of white flame. This affords an elegant and striking ex- 
periment. The metals, tin, zinc, copper, arsenic, and even 
gold, whor in the state of powder, or thin leaves, will be in- 
flamed in the same manner. 

Chlorine has a very strong attraction for hydrogen, but it 
is through the mysterious influence of light that the combi- 
nation between the two substances seems spontaneously to be 
effected. 

Thus, when a mixture of these two gases is kept in the 
dark, no combination ensues, but if exposed to the direct 
light of the sun, they combine suddenly, and with a violent 
detonation. 

This gas, though formerly called an acid, does not appear 
to possess any acid properties. It is not sour to the taste, 
nor does it redden vegetable blue colors, properties nearly 
universal in the acids. 

But the most important property of chlorine, is its bleach- 
ing power, all vegetable and animal colors being discharged 
by its action. For this purpose, it is combined with quick- 
lime, forming chloride of lime, or bleaching powder, an arti- 
cle very extensively employed at the present time, and which 
will be described, and its properties examined, in its proper 
place. 

Another very important property of chlorine is its disin- 
fecting power, any infectious or disagreeable odor being al- 
most instantly destroyed hy it. For this purpose, the chloride 
of lime is also chiefly employed. The compounds of chlo- 
rine which are not acid, are called chlorides, or chlorurets. 
When chlorine, united to oxygen, combines with a base, and 
forms a salt, it is called a chlorate. These w^ere formerly 
called hyperoxymuriates. They possess no bleaching proper- 
ties. 



In what manner may a shower of flame be made by this gas and a metaH What is 
said of the union between this gas and hydrogen? Does chlorine contain any of the pro- 
perties of an acid % What is the most important property of chlorine % What does chlo 
rine form, when combined with quicklime % What other important and useful property 
has this gas 1 WTiat are the compounds of chlorine, which are not acid, called 1 



166 CHLORINE AND HYDROGEN. 

CHLORINE AND HYDROGEN. 

^"^■^ Muriatic Acid — 37. 

1 p. Chlorine 36+1 p. Hydrogen 1. 

We have just seen that chlorine has a strong affinity for 
hydrogen, but that no union takes place between them, with- 
out the influence of light. When the light is entirely exclu- 
ded, a mixture of these gases remains without change. 
When the mixture is made in a glass vessel, and exposed to 
the light of day in the shade, the gases, if of equal volumes, 
slowly combine, and form muriatic acid gas. But when the 
mixture is exposed to the direct rays of the sun, the union is 
sudden, and attended by an explosion. 

This combination does not change the volume of the origi- 
nal mixture, but the properties of the two gases are greatly 
changed. If the vessel in which the experiment has been 
made is unstopped under water, the fluid will in a few mo- 
ments entirely absorb its contents, and fill the vessel in its 
place, while the two gases, before combination, were absorbed 
by water only in small proportions. The peculiar odor of 
chlorine, and its prompt bleaching property, are also destroy- 
ed, and other change of properties will become apparent on 
further examination. 

The compound formed by the union of chlorine and hy- 
drogen is called muriatic acid gas. This gas is composed 
by weight of 

1 equivalent of chlorine 36 
1 do. of hydrogen 1 

Combining weight of muriatic acid gas 37 
The production of muriatic acid by the combination of its 
elements, is designed to prove its constitution, and combining 
proportions. This acid is, however, much more readily pre- 
pared, by the action of sulphuric acid on common salt. 

If the salt be pulverized and mixed with an equal weight of 
the acid, and then the heat of a lamp applied, muriatic acid 

When a mixture of hydrogen and chlorine is kept in the dark, what change takes 
place 7 When placed in the shade, what is the effect 1 When the mixture is placed in 
the sun, what effect is produced 1 What are the changes produced on these gases by this 
combination 1 What is the name of the new gas 7 Wliat is said of the absorption by 
water of chlorine, and hydrogen, and also of muriatic acid gas 2 Whai is the composition 
of muriatic acid gas, and what is its combining number 1 How is this gas most readily 
and conveniently preparetl 7 



CHLORINE AND OXYGEN. 167 

gas will be disengaged. But it must not be received over 
water, which will absorb several hundred times its own bulk 
of this gas. 

Muriatic acid gas is a transparent, elastic fluid, of a very 
pungent smell, and intensely acid taste. Its attraction for 
water is'oO great, that when it escapes in the open air, even 
in the dryest season, it instantly forms a white cloud, in con- 
sequence of combining with the moisture of the atmosphere. 

Water, at the temperature of 40*^, absorbs 480 times its 
bulk of this gas, and the solution is known under the name 
of muriatic acid, or spirit of sea salt, and is largely employ- 
ed for chemical and manufacturing purposes. 

This acid is prepared, in the large way, by extricating 
ehe gas from sea salt, by sulphuric acid, as above described, 
and then passing a current of it into water, as long as any is 
absorbed. It forms, with the different bases, a class of salts, 
called muriates. 

When this gas, in a pure state, is submitted to the pressure 
of 40 atmospheres, that is, 600 pounds to the square inch, it 
is condensed into a liquid. 

CHLORINE AND OXYGEN. 

There are four compounds of chlorine and oxygen, formed 
by the union of as many different proportions of the oxygen 
to the same proportions of chlorine. These compounds are 
known only to chemists, and with the exception, perhaps, of 
chloric acid, possess no value in the art They are all form- 
ed by the action of an acid on the chlorate of potash, or the 
chlorate of barytes. The chief interest which these sub- 
stances possess, in a chemical relation, is their strict con- 
formity to the laws of definite and multiple proportions. 
Their names and constituents are as follow : 

Protoxide of chlorine, 36 chlorine/ + 8 oxygen. 
Peroxide of chlorine, 36 " 1^-1-32 " 
Chloric acid, 36 " +40 

Perchloric acid, 36 " +56 



Why does muriatic acid gas fcrm a white cloud in the open air ? How many times 
Its own bulk of this gas will water absorb 1 Under what name is this solution of gas in 
vv^ater known 7 How is the muriatic acid of commerce prepared 1 Under what pressure 
is this gas condensed into a liquid 7 How many compounds of chlorine and oxygen are 
known 7 Do the compounds of chlorine and oxygen possess any value in the arts 7 Id 
what relation are the compounds of chlorine and oxygen interesting 7 



168 CHLORINE AND NITROGEN. 

Thus, the first is composed of 1 proportion of chlorine 
combined to 1 of oxygen. The second, 1 of chlorine and 4 
of oxygen. The third, 1 of chlorine and 5 of oxygen. 
The fourth, 1 of chlorine and 7 of oxygen. 

The equivalent numbers, therefore, for the first, is 36+8= 
44; the second, 36+32=68 ; for the third, 36+40=76 ; and 
for the fourth, 36+56=92. 

CHLORINE AND NITROGEN. 

Chloride of Nitrogen — 158. 
4 p. Chlorine 144+1 p. Nitrogen 14. 

This curious compound was discovered by Dulong, a 
French chemist, in 1811. Chlorine and nitrogen have but 
a very slight affinity for each other, but they may be made to 
combine, by passing a current of the first through a solution 
of nitrate of ammonia. (Nitric acid, it maybe remembered, 
consists of the two elements, oxygen and nitrogen, and am- 
monia is composed of hydrogen and nitrogen. By the union 
of these two compounds, nitrate of ammonia is formed.) To 
prepare chloride of nitrogen, dissolve an ounce or two of the 
nitrate of ammonia, in 14 or 16 ounces of hot water, and when 
the solution has cooled to about 90 degrees, invert in the solu- 
tion a glass jar, with a wide mouth, filled Avith chlorine. The 
solution gradually absorbs the chlorine, and consequently, 
rises in the jar, at the same time acquiring a yellow color. 
In about half an hour, minute globules, of a yellow fluid, like 
oil, are seen floating on its surface. These, by uniting, ac- 
quire the size of small peas, when they sink to the bottom of 
the vessel. These globules are the chloride of nitrogen. 
They are formed by the decomposition of the ammonia, in 
the solution ; the chlorine combining with its nitrogen, and 
thus forming the compound in question. A cup of lead, or 
glass, should be placed at the bottom of the solution, and 
under the mouth of the jar, to receive the product. 

The chloride of nitrogen is the most violently explosive 
substance yet discovered, and should not be experimented 



What is the atomic weight, or chemical equivalent of chlorine 1 What are the name^ 
and what the combining numbers, of the four compounds of chlorine and oxygen 1 Wliat 
IS said of the affinity between chlorine and nitrogen 1 What is the composition of nitrate 
of ammonia 7 How is the chloride of nitrogen prepared 7 What chemical changes take 
place in the formation of chloride of nitrogen "? What cautions are given with respect 
tx) 9xperimenting on this compound ) 



IODINE. 169 

upon by the student, in quantities larger tnan a mustard-seed 
at a time, and even in this quantity, with great caution. Both 
its discoverer and Sir H. Davy, notwithstanding their expe 
rience and caution as chemical experimenters, were seriously 
injured t its violence. At the temperature of about 200 de- 
grees, it explodes, and at common temperatures, when thrown 
on some combustible. When a small globule is thrown into 
olive oil, or spirit of turpentine, it explodes with such vio- 
lence as to shatter any vessel of glass in pieces. 

The violence of its detonation is owing to the great vo 
lume of the products which are formed at the instant. The 
compound consists wholly of the two gases, chlorine and ni- 
trogen, condensed, and combined with each other. When, 
therefore, the explosion takes place, these two elements as- 
sume their gaseous forms, thus, in an instant, occupying a 
vast space, when compared to their former state. 

Chloride of nitrogen consists of 

1 equivalent of nitrogen 14 
4 do. of chlorine 144 



Making its number, 158 ^^-- 

lODINE 124. 

The next simple substance we shall examine, is iodine. Its 
name signifies, in Greek, "violet colored," because, when in 
the state of vapor, it is of a most beautiful violet color. 

Iodine Avas discovered at Paris by a manufacturer of nitre, 
in 1812. This substance is obtained from the ley made of 
the ashes of marine vegetables, or from the substance called 
kelp or barilla, which is an impure alkali, made during the 
manufacture of soda. The process is as follows : 

Dissolve the soluble part of kelp, or the ashes of sea-weeds 
ni water ; concentrate the solution by evaporation, when crys- 
tals of carbonate of soda w^ill appear, which must be sepa- 
rated. Then pour the remaining liquor into a clean vessel, 
and mix wdth it an excess of sulphuric acid. Boil this liquid 
for some time, and then strain it throuo-h a cloth. Put this 



At what temperature does this compound explode? What combustible substances 
cause it to explode at common temperatures 7 Explain the cause of its violent explosion. 
What arejthe combining numbers for its constituents, and also for the compounal What 
(joes Ike name iodine signify, and from wliat circumstance has it derived its name I By 
what process is iodine prepared 1 What is the apt^earance of io<line 7 

15 



170 IODINE. 

liquid into a small flask, and mix with it as much black ox- 
ide of manganese by weight, as there was sulphuric acid ; 
then attach to the mouth of the flask a glass tube, closed at 
the upper end, and apply the heat of a lamp to the flask. 
The iodine will be sublimed, and will attach itself to the tube 
in small brilliant scales resembling black lead. 

Iodine thus obtained is a friable solid, with a brilliant me- 
tallic lustre, and bluish gray color. Its taste is hot and acrid, 
and it is sparingly soluble in water. It corrodes the cork of 
the vial in which it is kept, and escapes — is a strong poison 
when taken in large doses : but in solution with alcohol, 
which dissolves it freely, has been considerably used as a 
medicine. 

When heated in a retort to about 250 degrees, it evaporates, 
and fills the vessel with an exceedingly rich violet colored 
gas. As the retort cools, it again condenses in fine brilliant 
points resembling frost on the glass. If exposed to the open 
air it slowly evaporates, and if handled, it leaves a brown 
stain on the fingers. 

Iodine resembles chlorine in smell, and in some of its pro- 
perties, particularly in destroying vegetable colors. Like 
oxygen and chlorine, it is a non-conductor of electricity, and 
is a negative electric. So far as is known it is a simple body. 
It has a strong attraction for the pure metals, and the simple 
non-metallic substances, such as sulphur and phosphorus. 
These compounds are called iodides. 

From experiments made by Dr. Thompson, the atomic 
weight of iodine is 124. 

The best test for iodine in its free state is starch, with which 
it forms an insoluble compound in water, of a deep blue co- 
lor. This test is so delicate as to indicate the most minute 
portion of starch in solution. 

Iodine combines with hydrogen, oxygen, and chlorine, 
forming hydriodic acid, iodic acid, and chlor iodic acid. Among 
these, the hydriodic acid, only, is of any importance or use. 



Wliat are its sensible properties? "What are its uses ? What is the effect when it Is 
heated in a retort 1 When exposed to the open air what is the consequence 1 In what 
respects does iodine resemble chlorine 7 What is its electrical state 7 Is iodine a simple 
or a compound body 7 For what substances has iodine a strong attraction 7 What is 
the atomic weight of iodine 7 What is the most delicate test for iodine 7 



IODINE AND HYDROGEN. 171 



IODINE AND HYDROGEN. 



Hydrioclic Acid — 125. 
1 p. Iodine 124+1 P- Hydrogen I. 

When iodine is heated in a porcelain tube with hydrogen 
gas, the two substances combine and form a compound in the 
form of a gas, which has acid properties, and which is rapidly 
absorbed by water. This is the hydriodic acid. 

This gas is without color, is very sour to the taste, reddens 
the blue colors of vegetables, and has an odor similar to 
muriatic acid gas. 

It combines with alkalies, forming salts, called hydriodates. 

The discovery of iodine was one of the means of subvert- 
ing the former doctrine, that oxygen was the universal acidi- 
fying principle, the above instance showing that compounds, 
having all the properties of acids, are formed by the combi- 
nation of hydrogen with iodine. Several other instances of 
similar nature have been discovered, as in the case of mu- 
riatic acid. These instances appear, however, to be only ex- 
ceptions to a universal principle, oxygen being still the ac- 
knowledged agent by vvhich most acids are formed. 

Hydriod.ate of Potash. This is given a place here, instead 
of among the salts, because it is the only salt of the kind to 
be described, and because, in manufacturing this compound, 
the method of obtaining the hydriodic acid is different from 
that stated above. It is the only hydriodate of any use or 
importance, and does not exist as a salt in a separate state, 
but only in solution. 

In preparing hydriodate of potash for medicinal use, the 
preliminary labor of forming the acid may be dispensed 
with, and the salt in solution, may be formed by a very simple 
process, as follows : 

Add to a hot solution of pure caustic potash in water, as 
much iodine as it is capable of dissolving. This will form a 
solution of a reddish brown color, consisting of the iodate 



How may hydriodic acid be formed 1 What are its sensible properties 1 What are the 
«alts called which this acid forms with alkalies'? How does this acid demonstrate that 
oxygen is not the universal acidifying principle 1 Are there any other instances in which 
an acid is formed without oxygen 7 What is said relative to these exceptions to a general 
principle 1 How is the hydriodate of potash formed ? What does the reddish brown solu 
lion consist of ? 



178 BROMINE. 

and hydriodate of potash, together with an excess of free 
iodine. 

Through this solution, a current of sulphuretted hydrogen 
gas is transmitted, until the free iodine and iodic acid are 
converted into hydriodic acid, changes which may be known 
to be accomplished by the appearance of the liquid, which 
will gradually lose its brown color, and become colorless and 
transparent. The solution is then heated to expel the re- 
maining sulphuretted hydrogen, and after being filtered, is 
pure hydriodate of potash, in aqueous solution. This solu- 
tion is considerably employed, as a medicine, in scrofula, and 
other glandular diseases. 

BROMINE 75, 

The name bromine is from the Greek, and signifies a 
" strong, or rank odor." 

Bromine, after undergoing various and multiplied tortures, 
by means of the most powerful decomposing agents, is ar- 
ranged as an elementary body, having endured fire, galva- 
nism, &c., without loss of integrity. 

It w^as discovered by Balard, of Montpelier, in 1826, and 
like iodine, exists in the ashes of marine vegetables, and also 
in sea water. 

The process of extricating it is too intricate to be detailed 
in this work, nor would it ever be undertaken by pupils in 
chemistry, for which this book is designed. 

Bromine is a fluid of a hyacinth red color, when viewed 
by transmitted light ; but of a blackish red, when se^n in the 
ordinary manner, or by reflected light. Its odor resembles 
that of chlorine, but is much more disagreeable. Like iodine, 
it corrodes wood or cork, and stains the fingers of a yellow- 
ish hue. Its specific gravity is 3. It is a strong poison. 
It is volatile at common temperatures, and emits red vapors 
similar to those of nitrous acid. 

A lighted taper is soon extinguished by it, but before going 
out it burns with a flame which is green at the base and red 
at the top. 



How is it known when a sufficient quantity of sulphuretted hydrogen has been passed 
through the solution of iodine 1 What is the use of the hydriodate of potash 1 What 
«loes the name bromine signify 7 Is it an element, or a compound ? In what substanco 
does it exists What is the appecurance of bromine 1 In what respects is it siiu'Iar to 
iodine? 



FLUORIC ACID. 173 

Bromine does not turn blue vegetable colours red, but like 
chlorine, destroys them. 

From these properties it will be observed, that this new 
substance has many characters in common with iodine and 
chlorine# 

Bromine combines with oxygen, hydrogen, and chlorine, 
but these compounds are little known, and of no interest ex- 
cept to professed chemists. 

Its equivalent number, as seen at the head of this section 
is 75. 

Fluoric Acid — 10. 

It is a singular circumstance in chemistry, that the base of 
the fluoric acid has never been detached from the acid 
itself, notwithstanding every effort has been made on the 
part of the chemists to effect a separation. It will be re- 
membered, that all the other acids consist of a base united to 
an acidifying principle, and that the two elements have been 
examined in separate states. Thus, sulphuric acid consists 
of sulphur and oxygen ; carbonic acid, of carbon and oxy- 
gen, &c. 

The base of this acid, however, has been n^med fluorine, 
but whether this is united to oxygen, as the acidifying prin- 
ciple, or whether such a base exists or not, is unknown. Flu- 
oric acid must, therefore, at present, be examined as a simple 
body, or in connection w4th substances to which it unites. 

This acid exists in nature in considerable quantities, being 
found combined with lime, forming the salt called fluate oj 
lime, but more commonly known under the nam.e of Derbyshire 
spar. This latter substance is found crystallized, and of va- 
rious colors intermixed, forming, when polished, one of the 
most beautiful productions of the mineral kingdom. It is in 
common use, for vases, candlesticks, snuff-boxes, &c. 

To obtain fluoric acid, a quantity of fluate of lime is pow- 
deied, and submitted to the action of twice its weight of strong 
sulphuric acid, in a retort of lead. On the application of a 
gentle heat to the retort, the acid distils over, and must be 
received in a leaden vessel. 



In what respect does it resemble chlorine in properties ? What is the equivalent num- 
oer of bromine ? Has the base of fluoric acid ever been detached from the acid itself 1 
Is the same true of any of the other acids 7 What is the base of fluoric acid called 1 Is 
H known that any such base exists ? Wliat natural substance contains fluoric acidl 
How is fluoric acid obtained from fluate of lime 1 

15* 




15?4 PLTJbRlC ACID 

^S- 59. The retort, and receiver, Pig 

59, made of sheet lead, and 
^soldered together on the edges, 
and the juncture between them 
stopped with a lute of clay, will 
answer very well. The white fluor must be selected for this 
purpose, as being most pure. It is first put into the retort^ 
the acid poured in, and then connected w4th the receiver, 
which must be surrounded with a mixture of common salt 
and snow, or powdered ice. 

Fluoric acid, at the temperature of 32°, or the freezing 
point, is a colourless liquid, and will retain its liquid state, 
if preserved in well stopped vessels, when the temperature is 
60°. But if exposed to the air when the temperature is 
above 32°, it flies off in dense white fumes, which consist of 
the acid, and the moisture of the air with which it com- 
bines. 

No substance with which we are acquainted has so strong 
an affinity for water as fluoric acid. Its liquid state appears 
to be owing to the water which is distilled over from the sul- 
phuric acid during the process of obtaining it, and no process 
yet devised has succeeded in freeing it entirely from mois- 
ture. When a single drop is let fall into water, a hissing 
noise is produced, like that occasioned by the plunging of a 
red hot iron into the same fluid, such is the heat produced 
by its combination with Avater. 

In experimenting with this fluid, the utmost caution is ne- 
cessary ; for no substance so instantly and effectually disor- 
ganizes the flesh, and produces such deep and obstinate ulcers, 
as this. The least particle would inevitably destroy an eye, 
or create an obstinate ulcer on any other part. 

Fluoric acid has the singular property of corroding glass, 
and may be used for this purpose in the fluid state, as above 
described, or in the gaseous form, the latter of Avhich is com- 
monly the most convenient. 

Any design may be etched on glass, by the following sim- 
ple method : 

First, cover the glass with a coat of bees wax, or engravers* 



What is the appearance of fluoric acid at the temperature of 32 degrees 1 Wliat is it* 
appearance when exposed to the open air, at a temperature above 32 degrees 1 What la 
said of the affinity of this singular acid for water? What is said of the action of this 
acid on the flesh ? What is said of the action :>f fluoric ar,id on glass 7 Describe the 
method of making designs on glass. 



CARBON AKD HYDROGEN. 175 

tarnish. If wax is used, it must be spread over the surface 
as thin as possible. This is done by heating the glass over 
a lamp, and at the same time rubbing it with wax. A thin 
and even coat may thus be obtained. 

NexU iraw the design by cutting the wax with a sharp 
pointed instrument, quite down to the glass, so that every line 
may leave its surface naked ; otherwise the design will be 
spoiled, since the acid will not act through the thinnest film 
of the wax. A large needle answers for a graver for this 
purpose. 

Having made the design, the etching is done by placing 
the glass in a horizontal position and pouring on the liquid 
acid. But a simpler method is the temporary extrication of 
the gas from the fluor spar, for the occasion. For this pur- 
pose, take a lead or tin cup, large enough to include the 
figures on the glass, the lower the better, and having placed 
on its bottom a table spoonful of powered spar, pour on it a 
quantity of strong sulphuric acid sufficient to form a paste. 
Then place the glass on the cup, as a cover, with the etching 
downwards, and set the cup in a dish of hot water, or apply 
to it the gentle heat of a lamp, taking care not to melt the 
wax. In twenty or thirty minutes the etching will be finished, 
^ and the wax may be removed with a little spirit of turpen- 
tine. In this manner, figures of any kind may be perma- 
nently and beautifully done on glass. 

COMBINATIONS OF SIMPLE NON-METALLIC COMBUSTIBLES 
WITH EACH OTHER, 

CARBON AND HYDROGEN, 

Carhuretted Hydrogen — 8 
I p. Carbon 6+2 p. Hydrogen 2. 

Light Cafbumtted Hydrogen, 

This gas has also been called kpdfO'Carbttret, and heavy 
inflammable air. 

It exists in every stagnant pool of water, especially during 
he warm season, being generated by the decomposition of 
vegetable products. 

To obtain it from such places, fill a glass jar with water, 



After the design is formedj in what mannet is the etching done ? What are the namef 
ttnder which carhuretted hydrogen has been known 1 In what place has this gas been 
forine<i by the operati<m of nature? 



176 CARBON AKD HYDROGEN. 

and invert it in a stagnant pool or ditch; then stir the mud 
under it with a stick, and the gas will rise and displace the 
water in the jar. To preserve it for examination, slide a dish 
under the mouth of the jar while in the water, and then 
carefully raise, and carry the whole to thfe place of experi- 
ment. 

The gas so obtained is found to contain a proportion of 
carbonic acid gas, which may be removed by passing it 
through lime water. 

This gas is composed by weight of 

1 equivalent of carbon 6 

2 do. of hydrogen 2 



It is immediately destructive to animal life, and will not 
support combustion. It is highly inflammable, and burns 
with a yellowish blue flame, but owing to the carbon it con- 
tains, it gives considerably more light than pure hydrogen. 
Mixed with atmospheric air, like hydrogen, it detonates 
powerfully when inflamed. When burned with oxygen, the 
product of the combustion is water and carbonic acid. 

There appears to be several varieties of light carburetted 
hydrogen, or perhaps the diflerence may depend on a mixture ^ 
of the light and heavy kinds. If a volume of steam be sent 
through a red hot gun barrel filled with charcoal, the gas 
obtained diflers little in its illuminating powers from that ob- 
tained from stagnant pools. Nor is there any m.aterial dif- 
ference between these and that evolved by the burning of 
common wood, such as maple or beech, in a gun barrel. But 
if pine wood containing turpentine, be heated in the same 
manner, the gas obtained has much greater illuminating pow- 
ers, the brilliancy of the flame being nearly equal to that of 
oil gas. Now as by analysis there appears to be only two 
kinds, or varieties, of carburetted hydrogen ; in the first of 
which there is but one proportion, and in the second two 
proportions of carbon, it is most probable that these different * 
powers of illumination depend on a mixture of the two gases. 



How may it be obtained from stagnant pools of water ? What gas is commonly found 
mixed with this? What is the atomatic composition of carbm-etted hydi'ogen? How 
does it affect animal life and combustion 1 When burned, why does this gas gire a 
stronger light than pure hydrogen 1 What is said concerning the several varieties of car« 
Vwretted hydi'ogen. 



CARBON AND HYDROGEN. 177 

This g-as sometimes (exists in large quantities in coal mines, 
and is known by the miners mider the name oi fire-damp. 
The most shocking accidents have often occurred in conse- 
quence of the explosion of this gas in the mines, when mixed 
wath a^iAxOspheric air. In some mines, this gas flows from the 
coal beds in vast quantities, being obviously the product of 
the decomposition of water by the coal. But in what manner 
the water is decomposed, is unexplained. Did the process 
consist in the formation of sulphuric acid, in consequence of 
the oxygenation of the sulphur, and the subsequent action of 
this acid on the iron, of the sulphuret of iron, there would be 
formed sulphuretted, instead of carburetted hydrogen. 

There are no facts, it is believed, which warrant the suppo- 
sition, that in ordinary cases, the decomposition is consequent 
upon the heat, or ignition of the coal Possibly in such vast 
bodies of coal as are found to exist in some mines, the water 
is slowly decomposed, by gradually imparting its oxygen to 
the carbon, without the aid of heat 

We have already stated^ that when carburetted hydrogen is 
mixed with atmospheric air, and inflamed, a violent explosion 
is the consequence. In the coal mines of England, the mix- 
ture of atmospheric air and the gas in question, often produ- 
ces such an exp:osive compound. It appears that the miners 
have no certain means of ascertaining the presence of this 
gas, probably because, being much lighter than the atmos- 
pheric air, it at first rises to the roof of the mine, and then 
gradually descends towards the floor. As the miners Avork 
entirely by the light of lamps, one of v/hich is suflicient to 
set fire to the explosive compound existing throughout the 
whole cavern, it is obvious, that 2is soon ^m the hydrogen has 
mixed with the air near the floor of the mine in the explod- 
ing proportions, it must inevitably take fire. It can readily 
be imagined, particularly by those who have witnessed the 
detonation of a pint or two of this compound, that a quantity 
covering many acres of surface, and extending upwards in 
some places, at least, several hundred feet, must produce the 
most awful consequences. 



Under what name is this gas known, when it occurs in coal mines 1 In what manner 
« this gas formed in coal beds 1 What are the remarks on this subject ? What is the 
xsnsequence, when this gas is mixed with atmospheric air and inflamed 1 In what situa- 
4ons is it said that explosive compounds are thus formed 1 What is the reason that thfl 
itaiiaexfi sxb not aware of the eiisLaiacs of thi^ compound until .the whole takes fire ? 



178 CARBON AND HYDROGEN. 

Such explosions have often taken place in the coal-mines 
m different parts of England. That which happened in a 
mine called Felling colliery, in Northumberland, on the 25th 
of May, 1812, was attended with the loss of 92 lives, and 
spread poverty and wretchedness throughout the whole dis- 
trict. Most of these men had wives and children, Avho de- 
pended entirely on their daily labor for support, and who, 
in addition to the loss of their husbands and fathers, by so 
sudden and awful a death, were in a moment deprived of the 
means of subsistence. 

This mine had been wrought a century or more, and only 
a single accident from fire-damp had before happened, and 
this was so. trifling, as only to slightly burn two or three 
workmen. Twenty-five acres of coal had been excavated in 
this mine, and the number of men employed under ground, 
at the time of the accident, was 128. The explosion took 
place between the hours of 11 and 12 in the morning. The 
fire was seen to issue from two shafts leading to the mine, 
and called William and John, and at the same instant, the 
noise of the explosion, which was heard three or four miles, 
and the trembling of the earth, showed that an aw^ful acci- 
dent had happened there. 

The force of the expanded gas was such as to throw from 
the two shafts immense clouds of dust, and small coal, which 
rose high in the air, and also pieces of wood and working 
implements, which fell back near the shafts. As soon as the 
explosion was heard, the wives and children of the colliers 
came by hundreds to the place. But not a single person 
who was in the mine during the accident, was to be seen. 
Terror and dism.ay was pictured on every countenance; some 
were crying out for a father, some for a son, and others foi 
a husband. 

The machinery for entering the mine, being shattered by 
the blast, it was at first impossible to go down, but the urgency 
of the occasion soon impelled those present to find the means 
of entering the shaft ; and in about half an hour from the 
time of the explosion, 32 persons, all who remained alive out 
of 121, who were in the mine, Avere brought out. It appear- 
ed that of the whole number of the workmen, seven had 
come up, on different occasions, before the explosion, ami 
were unhurt. The wives and children of those who were 



What number of lives were destroyed by such an explosion at Fejling colliery in lS12t 



CARBON AND HYDROGEN. 179 

known to be still in the mine, waited in a most heart-rendmg 
state of anxiety, and those who had their friends restored, 
seemed to suffer nearly as much from excess of joy, as they 
had before done from suspense and grief These hurried 
away with their friends from the dismal scene, while those 
who were still in suspense, or whose hopes ended in the 
dreadful certainty that their husbands or fathers were indeed 
among the dead, still lingered about the place, silently endu- 
ring the torture of a forlorn hope, and uttering cries of agony 
and despair. 

As the fate of many of the men was still uncertain, because 
they were in different parts of the mine, from those who had 
been found alive, the exertions of those above were unremit- 
ted, and in the course of an hour or two, many hundred peo- 
ple had collected around the shafts, all anxious to do every 
thing in their power for the sufferers. But it was soon found 
that the pit in some places w^as still on fire, the gas probably 
continuing to burn as it was extricated from the coal. It was 
also found by those who attempted to descend, that where 
the mine was not on fire, it was filled with carbonic acid gas, 
the product of combustion, and that therefore it was impossi- 
ble for any person to make further examination without in- 
evitable death. Consequently all hope of finding any of the 
unfortunate persons alive, who were still in the mine, was 
abandoned, and it w^as proposed that the shafts should be 
closed, in order to extinguish the fire. But the wives and 
children of the sufferers, distracted at the idea of seeing their 
friends buried alive, and still entertaining hopes of their re- 
covery, made the most pitiful im.portuniiies against such a 
course, while others became frantic with rage, and accused 
those of murder who proposed it. The owners of the mine, 
therefore, in mercy to the feelings of these distracted wddows 
and orphans, waited until all were satisfied that no hopes re- 
mained of ever again seeing their friends alive, when the two 
shafts were closed with earth. 

To insure the extinguishment of the fire, the mine was kept 
i^losed fro^Ti the 27th of May until the 8th of July, on which 
day it was again opened and ventilated. On this occasion, 
the lamentations of the widows and orphans Avas again re- 
newed, and such w^as the crowd of people that assembled on 
the spot, some urged by feeling, and others by curiosity, that 
constables were in attendance to preserve order. Those who 
descended to search for the remains of these unfortunate suf- 
f-rers, found no difficulty in breathing the air of the mine^ 



180 SAFETY LAMP. 

but were struck with horror at the scene of destruction and 
mutilation which the explosion had occasioned. 

The search continued until the 19th of September, when 
91 bodies had been found, brought up, and interred, but the 
9 2d never was found. 

We have been thus particular in describing a single in- 
stance of the awful effects of the iire damp in mines, that the 
reader might fully appreciate the safety-lamp, an invention 
made by Sir Humphrey Davy, expressly for the purpose o^ 
preventing such explosions, and which has proved completely 
successful. 

Before the invention of this lamp, such explosions were 
more or less common, and all the mines were subject to them, 
though none has been attended with such destruction to hu- 
man life, as that of Felling colliery. In 1815, such an oc- 
currence happened in a mine at Durham, and destroyed 57 
persons, and in another mine, 22 persons were killed in the 
same manner. 

The invention of the safety-lamp was not owing to accident, 
but is the result of inquiries undertaken and pursued expressly 
for the purpose of protecting the miners from such horrible 
accidents as we have described above. 

' Sir Humphrey Davy commenced his inquiries, by deter- 
mining the proportions in w^hich carburetted hydrogen and 
atmospheric air, in mixture, produce explosions ; and found, 
that when the gas is mixed with three or four times its vol 
ume of air, it does not explode at all. When mixed with five 
or six times its bulk of air, it detonates, feebly, but when the 
air is in the proportion of seven or eight times the bulk of the 
gas, the explosion is most powerful ; and with fourteen times 
its volume of air, it still explodes, though slightly. He also 
found that the strongest explosive mixture would not take fire 
when in contact with iron heated to redness, or even to white- 
ness ; while the smallest point of flame, owing to its higher 
temperature, caused an instant explosion. 



What other accidents of the same kind are noticed ? Does it appear :hat all excavated 
coal mines are liable to such accidents 1 Who invented the safety-lamp, "vvhich protects 
the miners from such accidents 1 Was this invention accidental, or was the safety-lamp 
the result of inquiry and experiment 7 In what proportions did Sir H. Davy find thai 
carburetted hydrogen and comm.on air exploded with the least force, and in what pro- 
portions with the greatest force 1 What did Sir II. Davy discover in respect to the com- 
munication of flame through narrow tubes 1 



SAFETY LAMP. 18* 

But the most important step in this inquiry was deducea 
from the faci that flame cannot be communicated through a 
narrow tube. The fact itself was known before, but Sir H. 
Davy discovered, that the power of tubes, in this respect, is 
not necessarily connected with their lengths, and that a short 
one is as efficacious in preventing the transmission of flame, 
as a long one, provided its aperture be reduced in proportion 
to its length. Pursuing this principle, he found that fine 
wire gLcUze, which may be considered as an assemblage o 
exceedingly short tubes, was totally impermeable to flame ; 
and on making the experiment, it was found that a lighted 
lamp, when completely surrounded with such gauze, might 
be introduced into an explosive mixture, without setting it 
on fire. 

Thus the means of preserving the miners, a most useful 
and laborious class of people, from the dreadful efl^ects of the 
hre-damp, was at once developed. It only became necessary 
to surround their lamps with a fine net work of brass wire, to 
nisure their safety from explosion. This lamp also indicates 
the existence of danger ; for w^hen the fire-damp in the mine 
IS in a highly explosive state, it takes fire within the gauze, 
and burns there, while the light of the lamp itself is unseen. 
When the miners observe this indication of danger, they in- 
stantly leave the mine, for although the flame within the 
gauze will not communicate with the explosive mixture on 
the outside, Avhile the gauze is entire, yet as a high degree of 
~ ' heat would be kept up by the combustion 

within the lamp, the wire would soon be- 
come oxidated, and perhaps fall in pieces, 
when an instant explosion would be the 
consequence. 

The safety lamp is represented by Fig. 
60. The cistern a holds the oil, and is in 
all respects a complete lamp, with a spout 
at the side, for feeding it. On the top of 
this is set the cylinder of wire gauze, Z>, sup- 
ported by three iron or brass rods, to which 
is connected the disc, or cover c, and to 
the cover, the ring, or handle by which 
the whole is carried. The drawing d, is a 




On pursuing this inquiry, what did Sir H. Davy discover with respect to wire gauze? 
yn this principle, how was it discovered that the minei-s might be protected from explo- 
«ons ? In what manner do these lamps indicais the presence of danger 1 

16 



182 GAS LIGHTS, 

piece of wire passing through a tube, showing the manner in 
which the lamp is trimmed, and the wick raised, without 
making any dangerous communication between the outside 
and inside of the lamp. This tube passes through the cis- 
tern containing the oil. 

The reason why the wire gauze obstructs the communi- 
cation of flame is easily explained. We have already stated, 
that according to the experiments of Sir H. Davy, the heat of 
flame is greater than that of a metal heated to whiteness, for 
the former occasioned a mixture of air and gas instantly to 
explode, while the iron, though white hot, produced no effect. 
Now the metals are all rapid conductors of heat ; when, there* 
fore, the flame comes in contact with the wire, its tempera- 
ture is so reduced by the conducting power of the metal, as 
to be incapable of setting fire to the gas which is on the out- 
side. Any one may illustrate this principle, by holding a 
piece of wire gauze over the flame of a lamp, and then bring- 
ing his hand over this, as near the lamp as he can bear. Now 
on removing the gauze, he will find that he cannot for an in 
stant bear the additional heat. 

Bicarhuretted Hydrogen — 14. 
2 p. Carbon 12+2 p. Hydrogen 2. 

Olefiant Gas, 

To prepare this gas, mix in a capacious tubulated retort, 
three measures of alcohol, with eight measures of undiluted 
sulphuric acid, and then apply the heat of a lamp. This 
mixture turns black, swells, and emits bubbles of gas in abun- 
dance, which may be collected over water, in the same man- 
ner as described for hydrogen. 

Alcohol is composed of carbon, hydrogen, and oxygen. 
During this process, the oxygen of the sulphuric acid appears 
to combine with a part of the carbon of the alcohol, in con- 
sequence of which, sulphurous acid gas is evolved, and the 
hydrogen is set free. At the same time, the hydrogen com- 
bines with another portion of the carbon, and escapes in the 



WTiy does it become necessary for the men to leave the mine, when the explosive mix- 
ture burns within the gauze 7 Describe the safety lamp, as -epresented at Fig. 60, and 
point out the uses of its several parts. Explain ths reason w y tlie flame is not commu- 
nicated through the wire gauze. How may this principle bei lustrated by holding a piece 
oi wire gauze and the hand over a candle 1 How is olefiant or bicarhuretted hydrogen 
gas obtained 1 What is the composition of alcohol 1 



GAS LIGHTS. 183 

form of bioarhurexted hydrogen. Or perhaps the evolution 
of the olefiant gas is owing to the strong attraction which the 
sulphuric acid has f(jr the water which the alcohol contains, 
and by combining with which, the hydrogen and carbon are 
liberated. 

Olefiant gas is colorless and elastic. It possesses no taste, 
and when pure, little smell, though, w^hen not purified, it has 
a faint odor of ether. When mixed with oxygen and in- 
flamed, it explodes with violence. 

This gas is a little lighter than atmospheric air, 100 cubic 
inches weighing 29.64 grains. The weight of carbon in this 
composition is 25.41 grains, and the weight of hydrogen 
4.23 grains. 

Olefiant gas, therefore, consists of 

Grains. 

Carbon, by weight 24.31, or two atoms, 12 
Hydrogen, do 4.23, or two atoms, 2 



29.64 14 

This gas may be decomposed, by passing it through a red 
not porcelain tube, one proportion of carbon being deposited, 
in consequence of which, it is converted into light carburetted 
hydrogen, which, as we have already seen, contains only 1 
proportion of carbon to 2 of hydrogen. 

Gas Lights. 

The olefiant gas, when pure, (with perhaps a single ex- 
ception) gives the most brilliant and intensely luminous flame 
of any knovv^n substance. The illuminating powers of other 
gases depend chiefly, if not entirely, on the olefiant gas they 
contain. In all cases, the light of any inflammable gas is in 
exact proportion to the quantity of carbon it contains. 

The flame of pure hydrogen scarcely gives sufficient light 
to show the hour on a w^atch dial. When combined with one 
proportion of carbon, forming carburetted hydrogen, its light 
is greatly increased, and when combined with another pro- 



What are the chemical changes which take place during the production of olefiant gasi 
What are the sensible properties of this gas? Does it explode when mixed witli oxygen 
and inflamed 1 What is the weight of carbon, and what the weight of hydrogen, in this 
gas 1 What is the atomic composition and what the combining number of this gas 1 
How is olefiant gas decomposed and resolved into carburetted hydrogen 1 What is said of 
die briUiant light of the olefiant gas 3 Or what does the brilliancy of gas lights depend I 



184 GAS LIGHTS. 

portion, its light becomes perfectly fitted for the purposes of 
illumination. 

Gas light, for the purpose of illumination, was first made 
and employed by Dr. Clayton, an Englishman, in 1739, but 
from some unknown cause, was given up, and neglected for 
sixty years afterwards. At length, Mr. Murdock instituted 
a series of experiments on the subject, and the gas distilled 
from coal, began to be used, on a small scale, for lighting 
different factories in the vicinity of London. 

From that period, which was about 30 years since, gas 
lights obtained from coal, or oil, have gradually come into use, 
for the purpose of lighting streets, shops, and manufactories, 
in all parts of Great Britain, and is, at the present time, in 
common use on the continent of Europe, and in several parts 
of America. 

For many years, the gas lights of London, and other parts 
of England, were supplied entirely by the distillation of bitu- 
mmous coal ; but more recently, many of the gas works, in 
different parts of that kingdom, obtain their lights from oil 
In this country, also, oil gas is chiefly employed. 

In respect to the advantages of gas, on the morals of soci- 
ety, in great cities, Mr. Gray, in his Operative Chemist, says, 
•' From the more brilliant manner in which our streets (those 
of London) are lighted by gas, than they ever were or could 
be, by oil or tallow, there is a greater degree of security, both 
in person and property, for every class of honest men. Crimes 
cannot now be committed in darkness and secrecy : and as 
the risk of detection increases, the temptation to guilt is di- 
minished, and thus coal gas, by the brilliant light it sheds on 
our streets, has worked, and is now working, a moral reform- 
ation. The house-breakers and pick-pockets dread the lamps 
more than the watchmen, and a more efficacious measure of 
police was never introduced into society, than that from gas 
lights." 

Oil gas is obtained by distilling impure Avhale or other oil, 
in large cylindrical cast iron retorts. From four to six such 
retorts, which, in appearance, resemble 24 pound cannon, are 
placed across a furnace built of brick, and are all heated by 



When were gas lights, for the purpose of illumination, fii-st employed? From wha; 
substance was gas lights first obtained 1 What is the substance now employed in this 
country, and in some parts of England, for this purpose 1 What is said of t!ie influence 
of gas lights on the morals of London 1 How is oil gas manufactured 7 Descnbe the 
furnaoe and retorts. 



Gils LIGHTS. 185 

the same fire. These are half filled Avith pieces of brick, or 
iron, in order to increase the surface, and thus to eflfect the 
decomposition of a greater proportion of the oil. The oil is 
contained in a reservoir placed so high as to run to the re- 
torts through a tube, of which each retort has a separate 
branch. The oil is admitted into the retorts on the outside 
of the furnace, the quantity being regulated by a stop-cock, 
with which each is furnished. On the opposite side of the 
furnace, the gas is conducted from each retort by separate 
tubes, which afterwards join in a common tube of larger size, 
and thence is conveyed to the gasometer. The oil is admitted 
into the retorts in a very small stream, or sometimes only by 
drops, and is decomposed, and converted into gas as fast as 
it runs in.^^..^— 

In large works, the gasometer is of immense size, being 
30 or 40 feet in diameter, and 15 or 20 feet high, and capa- 
ble of containing from 12, to 20,000 cubic feet of gas. 

This is made of sheet iron, suspended by a chain, over a 
pulley, and counterbalanced by weights on the other side. 
This falls into a tank, or cistern, held together by iron hoops, 
which are drawn with great force around it by means of 
screws. The tank being filled with water, the gasometer is 
let down into it, while the air escapes by opening a valve in 
its top. When the air is all excluded the gas is conducted 
into the gasometer by a pipe coming from the retorts, and 
opening under the water. As the gas rises through the water, 
the gasometer is buoyed up, and rises also, and thus the vessel 
is filled with inflammxable gas instead of air. 

From the gasometer, which is the great fountain, the gas 
is conducted by one large iron pipe, laid under ground to the 
place or street where it is burnt. It is then conducted in 
smaller pipes through the different streets, and from these 
pipes it is conveyed to the houses and shops by small tubes ; 
and tubes of still smaller size convey it to the burners where 
the lights are wanted. 

Rosin has lately been used instead of oil, and is said to yield 
a gas fully equal in quality to that of oil, and at a much less 
expense. 

As the burners are stationary, in the ordinary mode oHight- 



How is the oil admitted into the retorts 1 In large works, what is the size c i4ie f«ip- 
meter i How is the gas conveyed into the gasometer 7 How is the gas conr i ♦^ 6-i3« 
the gasometers to the gas burners 1 What inconvenience is experienced in 1 ta » 
ordinary gas lights? 

16* 



\So GAS LiGHTg. 

ing with gas, there exists an inconvenience in its employment 
for the purpose of common household illumination, where 
the lights are often necessarily carried to different parts of a 
room, or from one room to another. There is also another 
inconvenience, which arises from the expense of laying con- 
ductors through streets where the houses are scattered, and 
consequently, where but a small quantity of the gas is want- 
ed. To remedy these defects in the ordinary method of light- 
ing with gas, it has, within a few years been proposed to con- 
dense the gas in strong copper, or brass lamps, at the gas 
works, and then transport them thus filled, to the houses, to 
supply the place of common lamps. This is distinguished 
by the name portable gas, and has been, and it is believed is 
still extensively, employed in London and its vicinity. 

To fill these lamps, there is provided a long iron pipe, at 
one end of which is a forcing pumpj which is also connected 
with another pipe leading from the gasometer, to the pump 
through which the gas is conveyed. The long pipe is fur- 
nished with short tubes placed at convenient distances apartj 
and communicating Avith its inside. These tubes are cut with 
screw threads, which fit the screws at the bottoms of the 
lamps, and on Avhich these vessels are screwed, to be filled. 
TJius by working the forcing-pump, the gas is brought from 
the gasometer, forced into the pipe, and from the pipe into 
the lamps, so that many are filled at the same time. There 
is a mercurial gauge connected with the pump, by which its 
pressure is shown, and consequently by which the amount of 
condensation of the gas in the lamps is indicated. The flame, 
in burning the gas, is regulated by turning a small screw, and 
the gas is prevented from escape at the bottom by a valvej 
and another screw. 

The gas obtained from oil, is much purer than that obtain- 
ed from coal. The latter cannot be burned until it is purified 
by being passed through lime water, m order to deprive it of 
the carbonic acid, and other impurities ; but the oil gas does 
not require any such process, being fit for use as it passes from 
the retort. 

The illuminating power of the oil gas is also much greater 



How has it been proposed to remedy this defect 1 Under what name is this condensed 
gas k-nown 1 In what manner are the portable gas lamps filled 1 How is it ascertained 
with what degree of force the gas is condensed in the lamps 1 Which is most pure, the 
gas obtained from oil, or that from coal 1 Which gas has the greatest illuminating power 
that from the coal, or that from oil ? 



HVDROGEN AND SULPHUR. 187 

than that of coal gas. According to the experiments of Mr. 
Accum, two cubic feet of coal gas will burn one hour, and 
give a quantity of light equal to three tallow candles, eight 
of which weigh a pound. But according to the experiments 
of Mr. Dewey, superintendent of the gas works of New- 
York, one cubic foot of oil gas will give light for one hour, 
equal to 8 candles, 6 to the pound. This agrees very nearly 
with the result of Mr. Ricardo's experiments, who found that 
a given quantity of oil gas was equal in illuminating power 
to four times the same quantity of coal gas. One gallon of 
clean whale oil will make 100 cubic feet of gas, which, aC^ 
cording to the above statement will burn 100 hours, and give 
as much light as 8 mould candles, 6 weighing a pound. Such 
an immense difference between the cost of gas, and other 
lights, would seem to indicate the propriety of establishing 
gas works in every village. But the expenses of erecting 
and tending small establishments of this kind, are such as not 
to yield any considerable profit to the owners. In this coun^ 
try, where 2,000, or 2,500 lights ate wanted in a compact 
town, perhaps gas -works, might be maintained. The ex* 

f)enses of erecting such works would be not far from the fol- 
owing, viz. 

'2i miles, 3 inch main pipe^ $7,500 

Gasometer and tank, 3,000 

Refrigerator and connections, 1,500 

One bench retorts, 6 in number, 3,000 
Labour to erect the works 3,000 



17,500 



HYDROGEN AND SULPHUR. 

Sulphuretted Hydrogen. 17. 
I p. Sulphur 16+1 p- Hydrogen 1. 

This gas may be procured by placing in a retort some suU 
phuret of antimony, or iron, and pouring on it sulphuric ot 
muriatic acid. The sulphur ets of these metals may be pre- 
pared by heating either of them, in filings or powder, with 



What is said to be the comparative difference between the inuminating power of ccal 
and oil gas 1 What quantity of gas is it said one gallon of oil will make, and how long 
will this gas burn 7 The cost of oil gas being much less than other lighta^ why are they 
rwJt universally used 1 How may sulphuretted hydrogen be procured 1 



188 HYDROGEN AND SULPHUR. 

sulphur ; or the natural sulphurets may be employed. The 
ehemical changes concerned m the formation of this gas, are 
as follows. The oxygen of the water which the acid con- 
tains unites with the metal of the sulphuret, which metal is 
then dissolved by the acid. Thus, the hydrogen of the w^ater, 
and the sulphur of the sulphuret, are both set at liberty, and 
having an affinity for each other, they combine, and escape in 
the form of sulphuretted hydrogen. 

Sulphuretted hydrogen, is a transparent, elastic gas, which 
both to the taste and smell, is exceedingly unpleasant and 
nauseous, its odor being similar to that of putrefying eggs. 
Under a pressure of 17 atmospheres, that is, under a weight 
equal to 255 pounds to the square inch, this gas is condensed 
into a colorless liquid, but again assumes its gaseous form, 
when the pressure is removed. 

This gas is instantly fatal to animal life, vrhen pure, and 
even when diluted with 1500 times its bulk of air, has been 
found so poisonous as to destroy a bird in a few seconds. 
Like hydrogen, it instantly extinguishes flame, but is itseli 
inflammable and burns with a pale blue flame. The products 
of its com.bustion are water and sulphuric acid. The compo- 
sition of this gas being hydrogen and sulphur, the water form- 
ed during its combustion is the product of the union between 
the hydrogen, and the oxygen of the atm.osphere, during the 
act of combustion ; while the sulphuric acid is formed, by the 
union of the oxygen of combustion with the sulphur. 

Sulphuretted hydrogen tarnishes silver, and even gold, and 
blackens paint, made with preparations of lead. This gas is 
often generated curing the decomposition of animal products, 
in sink drains and ditches, and hence the paint of white lead, 
about such places often becomes black in consequence. 
Eggs contain a small quantity of sulphur, which on boiling 
is converted into sulphuretted hydrogen, and hence a silver 
spoon is instantly tarnished by coming in contract with a 
boiled esfo-. 



What cliemical changes take place by which this gas is evolved ? Wliat are the sen- 
sible properties of this gas? Under what pi assure may this gas be condensed into a 
liquid 7 Does it remain liquid when the pressure is removed "? What is said of the poi- 
sonous effects of this gas 1 Wliat are the effects of plunging a burning candle into this 
gas 7 When this gas is burned, what are the products of combustion'? Whence come 
the water and sulphuric acid 1 \Vhat is its effects on the metals ? 



HYDROGEN AND PHOSPHORUS. 189 

The composition of sulphuretted hydrogen by weight, is as 
follows : 

100 cubic inches of this gas weigh 36 grains. 
This is composed of sulphur, 33.89 do. 

do. do. of hydrogen, 2.11 do. 

36.00 

HYDROGEN AND PHOSPHORUS. 

Phosphuretted Hydrogen — 13. 
1 p. Phosphorus 12+1 p. Hydrogen 1. 

This compound consists of hydrogen, in which is dissolved 
a small quantity of phosphorus. It may be formed in several 
ways. One of the most simple is the following : Into five 
parts of water put 15 or 20 grains of phosphorus, cut into 
small pieces. It must be cut under water to prevent its tak- 
ing lire. Then add one part of granulated zinc, and pour in 
three parts of sulphuric acid. 

The gas will instantly rise through the water in small bub- 
bles, and will take fire spontaneously on coming in contact 
with the air. Each bubble as it takes fire will form a hori- 
zontal ring of white smoke, which will gradually enlarge as 
it rises, until lost in the air. The cause of this curious ap- 
pearance is owing to the formation of a small quantity of phos- 
phoric acid by the combustion of the phosphorus, and which 
having a strong affinity for moisture, attracts it from the at- 
mosphere, and thus forms a little ring of dew, Avhich is visi- 
ble to the eye. 

Phosphuretted hydrogen may also be obtained by placing 
some pieces oi jphosjphwret of lime in water, when the gas will 
be extricated, and will rise through the water as above de- 
scribed. [See Phosphuret of Lime.] 

This gas detonates with great violence when mixed with 
oxygen, and forms a dangerous explosive compound with at- 
mospheric air ; consequently much caution is required in 
making experiments with it. 

When a bubble of phosphuretted hydrogen is allowed to 
mix with oxygen, a flash of the most vivid light is spontane- 

What is the composition of 100 cubic inches of this gas by weight ? How is phos- 
phuretted hydrogen formed 1 What singular property does this gas possess 7 How is 
the ring of white smoke accounted for, which rises after the combustion of a bubble of 
this gas 1 With what substances does phosohuretted hydrogen afford dangerous detona- 
ting compounds 1 



190 NITROGEN AND CARBON. 

ously proQuced, which, in a darkened room, resembles light- 
ning. The safest method of performing this beautiful ex- 
periment, is to let up into a small strong bell glass, or a thick 
glass tube, a few ounces of oxygen gas. Then, having col- 
lected a little of the phosphuretted hydrogen in a small vial, 
hold the bell glass in the left hand, with its mouth imder wa- 
ter, and with the right hand manage the vial, so as to let only 
a single bubble at a time escape into the oxygen. The deto- 
nation of each bubble will produce a considerable reaction on 
the bell glass, which will be felt by the hand. But if the ex- 
periment be performed as described, there will be no danger 
of an explosion. 

The gas above described is called ^er -phosphuretted hydro- 
gen, denoting, as already explained, the highest degree with 
which one body unites with another. It is so called to dis- 
tinguish it from the proto-phosphuretted hydrogen, which con- 
tains only half the quantity of phosphorus, and is a much less 
mteresting compound. 

Per-phosphuretted hydrogen consists of 

1 equivalent of phosphorus, 12 
1 do. hydrogen, 1 

13 

NITROGEN AND CARBON. 

Carburet of Nitrogen — -26. 
2 p. Carbon 12+1 p. Nitrogen 14. 

Cyanogen. 

By boiling together red oxide of mercury and prussian blue 
in powder, with a sufficient quantity of water, there may be 
obtained a compound which shoots into crystals, and which 
was formerly called prussioJe of mercury, but is now known 
by the name of cyanuret of mercury. 

When this salt is heated in a retort, it turns black, the cy- 
anogen passes over in the form of a gas, and the mercury is 
revived, or assumes its metallic form. 

This gas has a pungent, disagreeable odor, burns with a 
purplish blue flame, extinguishes burning bodies, and is re- 
duced to a liquid under the pressure of about three and a half 
^atmospheres. This gas must be collected over mercury. 

What directions are given for admitting bubbles of this gas into oxygen? Whai 
is the equivalent coinDOsition of per-phosphuretted hydrogen ? How may cyanuret 
of mercury be formed ? How is cyanogen procured I What are the properties ol 
tliis gas % 



PRUSSIC ACID. 191 

100 cubic inches of this gas weigh 55 grains, and is found 
to be composed of 

2 tfquivalents of carbon, 12 

I do. nitrogen, 14 



26 its combining number. 

Cyanogen, though a compound gas, has the singular pro- 
perty of combining with other substances, in a manner per- 
fectly similar to the simple gases, such as oxygen and hy- 
drogen. 

The term cyanogen, comes from two Greek words signify- 
ing to form blue, because it is an ingredient in Prussian blue. 
Hydrocyanic Acid — 27. 
1 p. Cyanogen 26+1 P- Hydrogen 1. 
Prussic Acid. 

Cyanogen is obtained by simply heating cyanuret, or prus- 
siate of mercury, as above described. Hydrocyanic, or prus- 
sic acid, is composed of cyanogen and hydrogen. It may be 
obtained, by heating in a retort a quantity of prussiate of mer- 
cury with two thirds of its weight of muriatic acid. During 
this process, there takes place an interchange of elements. 
The cyanogen of the cyanuret of mercury unites with the 
hydrogen, forming hydrocyanic acid, while a muriate of the 
peroxide of mercury remains in the retort. 

But a more common method of making prussic acid is the 
following : 

Mix together, in a convenient vessel, four ounces of finely 
powdered Prussian blue, two and a half ounces of red oxide 
of mercury, and twelve ounces of water. Boil the mixture 
for half an hour, now and then stirring it. The blue color 
will disappear, and the solution will become yellowish green. 
Filter the solution, and wash the residuum, by pouring on 
boiling water, in quantities sufficient to make up the loss bv 
evaporation, and let this also pass through the filter. 

Put this solution, which is a prussiate of mercury, into a 
retort containing two ounces of clean iron filings, then con- 
nect the retort with a receiver, and place them on a lamp fur- 



What IS the equivalent composition of this gas, and what is its combining number 1 
Wlience comes the name of this gasl How may hydrocyanic, or prussic acid, be formed 
by means of prussiate of mercury and muriatic acid'? What are the interchanges of 
elements which take place during this process 1 What is the more common method de- 
er bed for making Prussic acid 7 




192 PRUSSIC ACID. 

nace, as represented by Fig. 61, taking care thnt the juncture 
be made air tight, which may be done b}'' 
winding a Avet rag around the neck of the 
retort. Next, pour into the retort one ounce 
of sulphuric acid, diluted with three or four 
parts of water, and stop its tubulure by pass- 
ing in a straight glass tube, which had been 
ready prepared by being passed through a 
cork. Then light the lamp, and distil with 
I a slow heat, until three ounces of prussic 
acid is obtained. The receiver must be 
kept cold, and also from the light, by being 
U^ covered with a wet cloth. 

The fumes of this acid are exceedingly 
vl_.^' poisonous, and therefore the lamp furnace 

should be set in a fire-place during the process, so that they 
may escape up the chimney. There is a complicated inter- 
change of principles which take place in this process, which 
Scheele explained thus. In prussian blue the prussic acid 
exists in combination Avith iron. The red oxide of mercury, 
having a stronger attraction for this acid than the iron has, 
the prussian blue is decomposed, and a prussiate of mercury 
is formed, which is soluble in water. On the addition of the 
iron filings and sulphuric acid to this solution, the iron ab- 
sorbs the oxygen from the mercury, which is then precipita 
ted in the metallic form, and at the same instant the iron is 
thus oxidized, it is dissolved by the sulphuric acid formmg the 
sulphate of iron. Thus, the prussic acid is liberated, because 
it does not combine with the metals, but only with their ox- 
ides, and as the iron deprives the prussiate of mercury of its 
oxygen, the prussic acid remains free in the solution of the 
sulphate of iron, and being volatile, readily passes over into 
the receiver, by a gentle heat. 

The hydrocyanic acid thus obtained, is a perfectly color 
less, limpid fluid, and cannot be distinguished by the eye from 
distilled water. It has a strong odor, resembling that ol 
peach blossoms, and when much diluted has the taste of bit- 
ter almonds. 

Prussic acid is the most active and powerful of all known 



What is said of the poisonous quality of the fumes of this acid, and of the precautions 
to avoid them'? Explain carefully the complicated interchange of chemical principles 
that take place by this process. What is the appearance of the acid thus obtained ) 
What is the smell of this arid 1 What cases are mentioned of its poisonous effecta 



PRUSSIC ACID. 193 

poisons. A single drop placed on the tongue of a dog causes 
his death in a few seconds, and a servant girl who swallow 
ed a small glass of it, diluted with alcohol, fell down instant- 
ly, as though struck with apoplexy, and died in two minutes. 
A professor at Vienna, having prepared some of this acid in 
Its most concentrated state, by way of experiment, diffused 
some of it on his naked arm, and was killed thereby in a 
short time. 

These instances not only show^ the terrific and mysteriou 
effect which this substance has on die animal economy, but 
they also show what extreme caution is necessary in prepar- 
ing and using it. When much diluted, it has, how^ever, been 
considerably employed as a medicine, in cases of consump- 
tion, and often with good effect. 

Although the investigations of chemistry have developed 
this substance, than which, even lightning itself is scarcely 
more prompt, or sure, in destruction, still the wisdom of Om- 
niscience has connected circumstances w^ith its production 
and nature, Avhich, in a great measure, will always prevent its 
employment for criminal purposes. The process by which 
it is made, requires more chemical skill than generally falls 
to the lot of unprincipled and vicious persons ; and Avhen 
obtained, its active properties are so evanescent, as never to 
remain more than a week or two, without peculiar treatment. 
and sometimes it becomes nearly inert in a few days. The 
odor, also, which is distinguished in animals destroyed by it, 
is often the sure means of detection. 

The commencement of its decomposition is marked by the 
reddish brown color of the liquid, and, in a short time after, it 
becomes black, and deposits a thick carbonaceous substance, 
at the same time it loses its peculiar smell, and emits that of 
ammonia. In this state, the prussic acid has none of its for- 
mer properties, but becomes entirely inert and worthless. 

This substance possesses the sensible- qualities of an acid 
only in a very slight degree, being hardly sour to the taste, 
and producing but very little change in the blue colors of 
vegetables. It however performs the office of an acid in 



For what purposes is this acid employed when much diluted 1 What circumstances 
are connected w^ith the production and nature of this acid, which it is said will prevent 
its employment for wicked purposes 7 How does the acid appear while decomposing 1 
Does this substance possess the sensible qualities of an acid 7 In what respect does it 
perform Uic office of an acid 1 

[7 



194 pRtrsslc ACID. J 

combining with alkaline bases, forming salts, called prussiaies 
or hydrocyanates. 

The following is an example, by which the composition oi 
1 substance may be found, when one of its elements can be 
made to combine v/ith a third body, in a known proportion. 
By a previous experiment it was ascertained how much cya- 
nogen would combine with a given portion of potassium, the 
basis of potash. Then, Gay Lussac exposed to the action oJ 
100 measurers of prussic acid, heated so as to be in the state 
of vapor, a quantity of potassium precisely sufficient to absorb 
50 measures of cyanogen. By this process, cyanuret oi 
potassium was formed, and exactly 50 measures of the vapor 
of prussic acid was absorbed, leaving 50 measures of pure 
hydrogen remaining in the vessel in which the experiment 
was made. 

From this experiment, it appears that prussic acid is com- 
posed of equal volumes of cyanogen and hydrogen, and there- 
fore that they combine in the ratio of their specific gravities, 
that is, the weight of the vapor of prussic acid must be the 
combined weights of cyanogen and hydrogen, of an equal 
bulk. 

Now the specific gravity of hydrogen is known to be 
0.0694, and cyanogen gas, 1.8044, air being 1000. Cyano- 
gen, therefore, is 26 times as heavy, bulk for bulk, as hydro- 
gen, and since they combine in equal proportions, by volume, 
to form prussic acid, it follows that this acid consists of an 
atom of hydrogen united to an atom of cyanogen, and there- 
fore, that an atom of cyanogen gas is 26 times as heavy as 
an atom of hydrogen. Thus, the atomic weight of cyano- 
gen is 26, that of hydrogen being 1, and the specific gravity 
of the vapor of prussic acid being the medium between them, 
is 0.9369, because 0.0694, the specific gravity of hydrogen, 
added to 1.8044, the specific gravity of cyanogen, makes 



How did Gay Lussac know that exactly 50 measures of cyanogen were absorbed by the 
potasskim ? [Cyanogen combines with metals in the^same manner that oxygen does. 
See Cyanogen.] What was the quantity of hydrogen which remained after this absorp- 
tion ? From this experiment, what appears to be the composition of pnissic acid, by vo- 
lume ; and therefore, the vapor of prussic acid consists of the combined weights of what 
How does it appeal* that cyanogen is 26 times as heavy as hydrogen? Multiply 0.0694 
by 26. How does it appear that an atom of cyanogen is 26 times as heavy as one of hy 
drogen 7 [Because they combine in equal volumes, but cyanogen weighs 26 times th« 
most.] What then is the weight of an atom of cyanogen, that of hydrogen being 1 



'A 



CARBON AND SULPHUR. 195 

1.8738, ilie medium, or half of which is 0.9369, the specific 
gravity of the vapor of prussic acid. 

The composition of prussic acid may therefore be stated 
thus : 

By volume. By weight. 

Cyanogen 50 1.8044 26, one atom, 

Hydrogen 50 0.0694 1, one atom. 

100 -ici'd vapor. 27 atomic weight. 

Thus the atomic weight, or equivalent number for cyano- 
gen is 26, and that for prussic acid is 27. 

The above will serve as a practical example of the method 
of finding the atomic weight of a constituent, under similar 
circumstances. 

CARBON AND SULPHUR. 

Sulphuret of Carbon — 38. 
1 p. Carbon 6+2 p. Sulphur 32. 

This singular compound may be made by the following 
process. Place an earthen tube, of about an inch and a half 
in diameter, a little inclined across a chaffing dish, previous- 
ly nearly filled with small pieces of newly burned charcoal. 
To the higher end of this tub i adapt another tube of glass, 
filled w^ith small pieces of sulphur. The end of this tube, 
not connected with the one of earthen, must be stopped with 
a cork, through which passes a wire, the whole being made 
air tight. To the opposite end of the earthen tube, another 
glass tube must be connected, and so bent as to pass under 
the surface of some water, contained in a bottle. When 
every thing is thus prepared, the charcoal in the chaffing- 
dish is set on fire, and when the centre of the tube becomes 
red hot, the sulphur must be pushed forw^ard with the wire, so 
as to come in contact with the charcoal. The combination 
instantly ensues, and the vapor of sulphuret of carbon will 
condense under the water in the vessel. In this state it is of 
i yellowish color, but may be purified by redistilling in a 



What is the specific gravity of the vapor of prussic acid, it being the medium between 
.iiose of cyanogen and hydrogen 1 From these data, what is the composition of prussic 
eujid, by volume and weight 7 What is the equivalent number for prussic acid 1 Describe 
the process for making sulphuret of carbon. What is the color of the compound so pre- 
pared 7 How may it be purified, so as to become colorless and transparent 7 



196 METALS. 

retort containing a little muriate of lime, to absorb the water. 
The heat, during this process, must not be over 110^, and 
therefore, is best applied by a vessel of water over a lamp, in 
which the retort is placed. The neck of the retort is dipped 
under water, as before. 

The compound, thus obtained from two solids, the one black 
and the other yellow, is a perfectly transparent and color- 
less liquid. Its taste is acrid and pungent, and its smell ex- 
ceedingly fetid and disagreeable. Its specific gravity is 1.27, 
water being 1.00. It does not mix with water, but smks 
through that fluid, as water does through the lightest oil. 
It possesses very high refractive powers, {see Nat. Philoso- 
fhy,) and is so volatile as to produce an intense degree of 
cold by evaporation, when exposed to the open air. It is high- 
ly inflammable, and burns w4th a blue flame, emitting copious 
fumes of sulphuric acid. It dissolves phosphorus and iodine, 
the solution of the latter being of a beautiful pink color. 

It was stated a year or tw^o since in Paris, and republished 
in the journals of this country, that when this substance is 
mixed with phosphorus, and allowed to stand under water for 
six or eight months, the phosphorus combines Avith the sul- 
phur, thus, leaving the carbon to crystallize, and form real 
diamonds. Having left such a mixture, undisturbed, for a 
much longer period than the recipe directs, w^e have as yet 
discovered no appearance of this precious gem. 

Sulphuret of carbon is composed of 

1 equivalent, or atom, of carbon, 6 

2 do. do. sulphur, 32 



Its combining number, 38 



METALS. 

The metals form the most numerous class of undecomposed, 
or elementary bodies. They possess a peculiar lustre, called 
the metallic, which continues in the streak, or when they are 



In what respect does this compound show the mysterious effects of chemical combina- 
tion 7 What are the sensible properties of sulphuret of carbon 7 What is its specific 
gravity? What is said of its refractive powers, its volatility, and its inflammability 1 
What has been published concerning the method of making diamonds from this sub 
stance 7 What is the equivalent composition of sulphuret of carbon 7 What is its equi 
valent number 7 Have any of the metals been decomposed 7 What is the peculiar lu» 
tre of the metals called 7 



METALS. 197 

reduced to small fragments. They are ail conductors of 
electricity and caloric. They are fusible, at different tem- 
peratures, and in fusion retain their lustre and opacity. They 
are, in general, good reflectors of light, and with the excep- 
tion of gold, which, in the thinnest leaves transmits a green 
light, they are perfectly opaque. 

Many of the metals may be extended under the hammer, 
and are hence called malleable, or under the rolling press, 
and are called lamiiiable, or may be drawn into wire, and are 
called ductile. Others can neither be drawn into wire, nor 
hammered into plates, but may be ground to powder in a 
mortar ; these are called brittle metals. 

The metals are capable of combining with each other, in 
any proportion, when melted together, and such compounds 
are called alloys. 

With a few exceptions, the metals have the greatest spe- 
cific gravity of all bodies. Potassium and sodium swim on 
water, but with these exceptions, the lightest among them, 
cerium, is about 5 2" times the weight of water; platinum is 
more than 20 times heavier than the same bulk of water. 

The metals differ in respect to brilliancy, color, density, 
hardness, elasticity, ductility, tenacity, conductility for caloric 
and electricity, fusibility, expansibility by heat, stability, odor, 
and taste. 

When combined with oxygen, chlorine, iodine, or sulphur, 
and the resulting compounds submitted to the action of gal- 
vanism, the metals without exception are revived, and appear 
at the negative side of the battery, hence all the metals are 
'positive electrics. 

The malleable metals, such as gold, silver, and iron, in 
whatever manner their surfaces are increased, if this is done 
rapidly, grow hot, and crumble under the hammer, or press, 
and finally refuse to be extended any further. It then be- 
comes necessary, if their surfaces are to be farther extended, 
to anneal them, which is done by exposure to a red heat, 
when they become soft and malleable as before. It is pro- 



Wliat imponderable agents do all the metals conduct? Are all the metals opaque"? 
What are malleable, laminable, and ductile metals 1 What are brittle metals 7 What 
: is an alloy 1 What is said of the specific gravity of the metals 1 What are the proper- 
ties in respect to which the metals differ 1 What is the electrical state of the metals? 
When the surfaces of the malleable metals are suddenly increased, what effect \s thereby 
produced on their temperature 7 When is it necessary to anneal a metal 1 

17* 



198 METALS. 

bable that this change is produced by a quantity of caloric 
which the metal retains in its latent state, and by which its 
particles are prevented from forming so compact a mass as 
before. When the metal is again draw^n under the hammer 
or press, it grows hot, and at the same time is increased in 
density and specific gravity, the caloric before absorbed be- 
ing given out, and the metal is again rendered brittle by the 
process. 

All the metals are converted into a fluid state by sufficient 
degrees of heat. In this respect there is a vast difference 
m the different metals. Mercury is a fluid at all common tern* 
peratures, and does not assume the solid form unless exposed 
to a temperature nearly 40° below^ the freezing point, while 
platina and columbium continue solid under the highest heat 
of a smith's forge, and only become fluid under the heat of 
the compound blowpipe, or the action of the most powerful 
galvanic battery. 

With several exceptions, these bodies suffer a singular 
change on exposure to air and moisture, or on exposure to 
air and heat. They lose their tenacity, brilliancy, and other 
qualities peculiar to the metals, soil the fingers, and crumble 
to powder, but at the same tirr^ increase in weight. This 
change is termed oxidation, and in this state they are termed 
metallic oxides. 

This increase in weight and loss of metallic splendor, does 
not happen when the metal is placed in a vacuum, or when it 
is protected from the air by varnish or other means, but is 
found to be the consequence of the union between the metal 
and the oxygen of the air, or water, or both. Thus, irc^i, 
w^hen exposed to air and moisture, spontaneously absorbs 
oxygen and is converted into a brown friable matter called 
rust. This is an oxide of iron. The increase of weight is 
caused by the solid oxygen which thus combines with the 
m^tal. 

Metals, in the language of chemistry, are termed combiis- 
tibles, because they are capable of combining with oxyg3n, 



How is the process of annealing supposed to affect the metal, so as to restore its raallea- 
oility '? By what means may all the metals be rendered fluid ? What is said of the dil 
ferent temperatures at which the metals become fluid? The metals, with the exception 
of platina. gold, and silver, are said to suffer a peculiar change, when exposed to heat, oy 
to air and moisture. To what is this change owing, and what are the resulting com- 
pounds called 1 What causes iron and other metals to rust, when exposed to the airl 
Why are the metals termed combuptible in the language of chemistry'? 



METALS. 19t 

and thus passing through the process of oxidation, or com- 
bustion. In ordinary combustion there is an extrication Ox 
heat and light, and under favorable circumstances, several 
of the metals exhibit these pnenomena. Zinc burns with a 
brilliant flame when heated, and exposed to the open air ; and 
iron, when heated in oxygen gas, emits the most vivid scin- 
tillations, attended with intense heat. Gold and platina, the 
metals which have the least affinity for oxygen, are still ca- 
pable of uniting with it so rapidly, as to produce scintillations 
when heated with the flame of the compound blowpipe. In 
all cases the metals combine wdth oxygen most rapidly when 
exposed to the highest degrees of heat. Hence, at common 
temperatures, their oxidation proceeds so slowly as not to 
emit sensible light or heat ; and some of them, such as gold, 
silver, and platina, do not combine w^ith it at all at such tem- 
peratures. 

Some of the metals combine with oxygen in only one pro- 
portion, while others combine with it in three or four pro- 
portions. Thus, there is only a single oxide of zinc, but 
there are three or four oxides of iron. 

After the metals are converted into oxides, they may again 
be reduced, that is, brought back to their metallic states, by 
depriving them of their oxygen. This may be done by se- 
veral methods, depending on the nature of the metal, or the 
force by which it retains the oxygen. The reduction of many 
of the metals from their ores, is nothing more than depriving 
them of their oxygen. 

For this purpose, a common method is to heat the oxide 
with some combustible, which has a stronger affinity for the 
oxygen than the metal has. Thus, the oxide parts with its 
oxygen, and assumes the metallic form, while the combusti- 
ble absorbs that which the oxide before contained, and is 
itself consumed or ccn-^^erted into an oxide. As an example, 
carbon when heated has a stiunger affinity for oxygen than 
iron, and therefore, when carbon aud oxide of iron are 
strongly heated together, the iron is reduced vv'Mle the char- 



Under what circumstances do several of the rnetals exhibit the ordinary pheno- 
mena of combustion % Under what circumstances do all the metals combine most 
rapidly with oxygen 7 What metals do not combine at all with oxygen at common 
temperatures 1 Do the metals all combine with the sam.e proportion of oxygen 1 
A-fter a metal has been converted into an oxide, how may it again be reduced, oi 
brought again to its metallic state 1 By what method can the metals be deprived ol 
their oxygen 1 What is one of the most common methods of reducing iron from its 
ores 'I 



200 METALS. 

coal Is converted into an oxide, or an acid, and passes array 
into the air, or in common language, is burned up. This is 
the method of reducing iron from its ores. 

In some instances, heat alone drives away the oxygen and 
reduces the metal ; but in such cases the metal has only a 
weak affinity for oxygen. The oxides of gold, mercury, and 
platina, are thus reduced. 

Metals having stronger affinities for oxygen, resist such 
methods of reduction, and require the more powerful agency 
of galvanism. When metallic oxides are exposed to this 
influence, the reduced metal is found at the negative side ol 
the battery, Avhile the oxygen rises through the water at the 
positive side. 

None of the metals are soluble in an acid, in their metallic 
states, btit when first combined with oxygen they are readily 
dissolved. Gold will not dissolve in muriatic acid alone, 
because this acid does not part with its oxygen with such 
facility as to form an oxide of the metal. But if a quantity 
of nitric acid be added to the muriatic, the gold instantly be- 
gins to enter into solution, and a chloride of the metal is 
formed. If a piece of zinc be thrown into sulphuric acid, it 
will remain undissolved, but if three or four parts of water 
be poured in, the metal is attacked with great violence, and 
soon dissolved. In this case the water furnishes the oxygen, 
by which the zinc is oxydized, and it is then dissolved by the 
acid. By this method hydrogen is obtained ; the metal de- 
composing the water by absorbing its oxygen, while the hy- 
drogen is set at liberty. 

The metals combine with phosphorus, sulphur, and car- 
bon, forming compounds called phosphureis, sulphur ets, and 
carburets. 

Of all the inflammable bases, sulphur appears to possess 



VVhen iron is reduced by heating its oxide with charcoal, what becomes of the oxy 
gen? In what instances does heat alone reduce the metallic oxides? WTien me- 
tallic oxides are reduced by means of galvanism, at which pole of the battery is the 
oxygen extricated 1 Are any of the metals soluble in the acids, while in their metallic 
states 1 Why is it necessary to add nitric acid to the muriatic acid before it will dissolve 
gold? Why does not zinc dissolve in strong sulphuric acid ? Why is hydrogen evolved 
when the zinc is dissolved in diluted sulphuric acid? When a metal combines with 
phosphorc*?, what is the resulting compound called ? Wliat is the composition of a siil 
phuret? WTiat is the composition of a carburet? What combustible body appears to 
possess the strongest affinity for the metals 1 



METALS. 20 J 

tlie strongest affinity for the metals, and its combination with 
some of them is attended with remarkable phenomena. This 
affinity is shown by the following- interesting experiment. 
Introduce into a Florence flask, three parts of iron, or cop- 
per filings, and one part flowers of sulphur, well mixed to- 
gether. Then stop the flask with a cork, and place it over 
a lamp, so as to heat it slowly, and as soon as any redness 
appears, remove the flask from the fire. The chemical ac- 
tion thus begun, will be continued by the heat evolved by 
the combination between the sulphur and the metal, and the 
whole mass in succession will become red hot, which, in the 
dark, will produce a very beautiful appearance. 

We have stated, in a former part of this work, that when 
bodies pass from a rarer to a denser state, caloric is evolved. 

The heat and light, in this experiment, seems to be the 
consequence of this general law of condensation, for the sul- 
phuret, formed by the union of the two bodies, occupies 
much less space than the metal and sulphur did before. 

Many of the metallic sulphur ets are very abundant in na- 
ture, forming the ores of the metals. Several metals are 
extracted entirely from such ores. The most abundant sul- 
phurets are those of lead, antimony, copper, iron, and zinc. 

The phosphurets are seldom found as natural products, 
but may be formed, by bringing phosphorus into contact w^ith 
the metal, at a high temperature. 

Carbon unites with iron in several proportions. Unrefined 
iron, steel, and black lead, are all carburets of iron, the latter 
containing 95 per cent, of carbon. 

When the oxide of a metal is dissolved in an acid, there 
is a compound formed, which differs entirely from either of 
ihese two substances, and when the liquor is evaporated there 
remains a crystalline solid, called a metallic salt. These 
salts diflfer materially from each other, according to the kind 
of acid and metal of which they are composed. Some of 
them, such as the sulphate of iron, and acetate of lead, are of 
great importance to the arts. 

The oxides of the metals readily unite by fusion with glass, 



What experiment is 8tated,}illustrating the affinity between iron and sulphur 7 Whence 
does the heat arise in this experiment 1 What are the most abundant sulphurets in na- 
ture 1 Are the phosphurets often found native 1 What carburets are mentioned 1 Whai 
is a metallic salt 1 What particular salts are mentioned, as being of great imporl'^nce to 
the aits 7 What is said of the union between the metallic oxides and glass 7 



202 METALS. 

and it is by such means that this substance is made to re- 
semble gems and precious stones. The stained glass, so 
celebrated among the ancients, and used in the windows oj 
churches, was prepared in this manner. This art was said 
to have been lost, but stained glass is still made in many 
parts of Europe, and in this country. {See Glass.) 

Compounds, made by fusing two or more metals together, 
are called alloys. In these cases there is a chemical union 
between the metals ; and hence such compounds differ great- 
ly from the metals of which they are composed. In general, 
the specific gravity of the alio}'' is greater than the medium 
specific gravity of the two metals, and of consequence, the 
bulk of the alloy is less than that of the two metals taken 
separately. As an example, if two bullets of copper and two 
of tin, of equal bulk, be melted together, they will form little 
more than three bullets of the same size. This diminution ol 
bulk is accounted for, by supposing that the particles of the 
two metals enter into a closer union with each other, when 
combined, than those of either did in a separate state. 

The alloys of the metals are also more easily fusible than 
the metals of which they are composed ; that is, the melting 
point of an alloy is below the medium temperature at which 
the metals composing it are fusible. 

An alloy, made of 8 parts bismuth, 5 lead, and 3 tin, is a 
curious instance of this fact. In a separate state, the melting 
point of lead is 500°, bismuth, 490°, and tin, 430°, and yet, 
Vv'hen these are fused together, the compound melts at 212°. 
Amusing toys, in the form of tea-spoons, have been made of 
this alloy. Such spoons, in the hand of those who know no- 
thing of their composition, have excited great astonishment, 
by coming out of a cup of hot tea with their bowls melted off 

The number of metals, and the variety of properties Avhich 
they possess, render it necessary to throw them into classes 
and orders, that a knowledge of these properties may be more 
easily obtained. 

The following arrangement is that originally proposed by 
Thenard, and adopted by Henry and others. 

We have already stated, that some of the metals are redu- 
ced from the state of oxides by heat alone, such metals hav- 



What are alloys 1 In what respect do alloys differ from the metals of which they aro 
composed 1 How is the increased specific gravity of the alloys accounted for 1 What i» 
eaid of the fusibility of alloys 7 What curious illustration of the fusibility of an alloj 
made of bismuth, lead, and tin, is given i 



METALS. 203 

ing only a slight affinity for oxygen. Others, it was also sta- 
ted, have so strong an attraction for oxygen, that they cannot 
be reduced by this method, but require the presence of a com- 
bustible, or some other means, for their reduction. The ar- 
rangement into classes is founded on this distinctive difference. 
The orders of the second class are founded on the powers of 
tne metals to decompose water. 

Class I. — Metals, the oxides of which are reducible to the 
metallic state, by heat alone. These are 

Mercury, Platinum, Osmmm, 

Silver, Palladium, and 

Gold, Rhodium, Iridium. 

Class II. — Metals, the oxides of which are not reducible 
to the metallic state by the action of heat alone. 

Order 1. — Metals which decompose water at common tem- 
peratures. These are, 

Potassium, Lithium, Strontium, 

Sodium, Barium, Calcium. 

Order 2. — Metals which are supposed to be analogous to 
Order 1, but whose properties are but little known. These 
are, 

Magnesium, Ittrium, Zirconium, 

Glucinum, Aluminum Silicium. 

Order 3. — Metals which decompose water at a red heat 
These are, 

Manganese Iron, and 

Zinc, Tin, Cadmium. 

Order 4. — Metals which do not decompose water at any 

temperature. These are. 

Arsenic, Uranium, Titanium, 

Molybdenum, Columbium, Bismuth, 

Chromium, Nickel, Copper, 

Tungsten, Cobalt, Tellurium, 

Antimony, Cerium, Lead. 

Of the first class, there are 8 metals; of the second, there 

are 32; makinof 40 in all. 



Wliat is the distinctive difference between the metals, on which is founded the arrange- 
ment into classes 7 Wliat are the peculiar properties on w^hich the orders of the second 
AST. are founded 1 How are the classes and orders defined, and what are the names ol 
the metals belonging to each 1 How many metals belong to the first class and how many 
to the second. 



204 MERCURY. 

CLASS I. 

Metals, the oxides of which are decomposed by the actioi 
of heat alone. 

MERCURY— 200. 

Mercury, or quicksilver, is found native, or in its pure 
state, only in small quantities, the mercury of commerce being 
chiefly extracted from cinnabar, which is a sulphuret of the 
metal. The melal is extracted from this ore, by heating if in 
iron retorts, mixed with iron filings or lime. By this process, 
the sulphur combines with the lime or iron, forming a sul- 
phuret of lime or iron, while the mercury is volatilized, and 
is distilled into a receiver, where it condenses in its pure form. 

This metal is distinguished from all others by preserving 
Its fluidity at common temperatures. Its specific gravity is 
13.5. At the temperature of 660° it boils, rises in vapor, and 
may be distilled from one vessel into another. At 40° below 
zero it becomes solid, and is then malleable, and may be ham- 
mered into thin plates. 

When pure, this metal is not readily oxidized in the open 
air at common temperatures, but when mixed with other me- 
tals, such as tin, or zinc, there is commonly a film of oxide 
on its surface ; hence this is an indication that the mercury is 
impure. When mercury is triturated with an equal quantity 
of sulphur, there is formed a black powder, called ethiofb 
mineral. 

Mercury readily combines with gold, silver, tin, bismuth, 
and zinc ; but not so readily with copper, arsenic, and anti 
mony, and with platina and iron scarcely at all. The result- 
ing compounds between mercury and the other metals, are 
called amalgams. 

Mercury has such an aflinity for gold and tin as to dissolve 
these metals in small pieces, at common temperatures. In 
the mines of South America, a great proportion of the gold 



What is the definition of class first? From what substance is the mercury of com; 
merce extracted'? Wliat is the composition of cinnabar, and what its chemical name? 
What is the method of obtaining the mercury from its sulphuret ? Wliat striking dis- 
tinction is there between mercury and other metals ? What is the specific gravity of 
mercury 1 At what temperature does mercury boil, and at what temperature does il 
freeze? When solid, what property common to many other metals does it possess*? 
What are the obvious indications of impurity in this metal 1 What is ethiops mineral 1 
VViien mercury combines with other metals, what is the compound called 7 



MERCURY. 205 

was formerly procured by amalgamation. Sand containing 
particles of gold, was agitated in a close vessel with mercury, 
and the two metals thus brought in contact, united and formed 
an amalgam. This was then distilled in an iron vessel, by 
which the mercury was driven away, while the gold remained. 

At the present time, the gold-beaters make use of the same 
means to obtain the small particles of the metal contained in 
the sweepings of their shops. The sweepings being placed 
in a close vessel, and agitated with mercury, an amalgam i 
formed. The gold is then separated by pressing the amal- 
gam in a buckskin bag, which forces the mercury through 
the pores of the leather, while the gold is retained. 

Mercury is applied to many other uses in the arts, and is 
a constituent in several important medicines. 

The silvering on the backs of looking-glasses, is an amai 
gam of tin, and is put on in the following manner: A sheet of 
tin foil is laid perfectly smooth on a slab of marble, and on the 
tin foil, mercury is poured, until it is about the eighth of an 
inch thick ; the attraction of the metals for each other, keep- 
mg the mercury from running off When the mercury is 
spread equally over the surface, the glass plate is run or slid 
on. This is so managed, by partly immersing the end of the 
plate in the edge of the mercury, and pushing it forward, a? 
CO entirely exclude the air from between the metal and the 
glass. Weights are then laid on the plate, to press out the 
mercury which does not amalgamate with the tin. In about 
24 or 36 hours, the amalgam adheres to the plate in the 
manner we see it on looking-glasses. The glass, therefore, 
merely serves to keep the amalgam in its place, and being 
transparent, to transmit the image whi^h is reflected from the 
surface of the metal. Could the mercury be kept from oxy- 
dation, and be retained in its place without the glass plate, 
such mirrors would be much more perfect, since the glass 
prevents some of the rays of light from passing to and from 
the metal. 



How is gold obtained by mercury 1 How do gold-beaters obtain the small particles of 
go^Id from among the sweepmgs of tneir shops 1 AViiat is the composition called the stl. 
Fcring, on the backs of looking-glasses'? Describe the process of silrering a plate of 
In forming a looking-glass, what is the use of the glass plate 'i 

18 



206 Mercury 

mercury and oxygen. 

Peroxide cf Mercury — 216. 

1 p. Mercury 200+2 p. Oxygen 16, 

Red Precipitate. 

This compound is commonly formed by dissolving mercury 
m nitric acid, and then exposing the nitrate to such a degree 
of heat as to expel all the acid. It is in the form of small, 
shining crystalline scales, of a red color. When exposed to 
a red heat, this oxide is reduced, and converted into oxygen, 
and metallic mercury, a circumstance on which its arrange- 
ment in the present class depends. When long exposed to 
the action of light, the same effect is produced. Red pre- 
cipitate is employed in medicine chiefly as an escharotic. 

It will be observed at the head of this section, that the per 
oxide of mercury is composed of 200 parts of the metal com- 
bined with 16 parts or two equivalents of oxygen. The prot- 
oxide of this metal consists of 200 mercury, and 8 oxygen, 
these compounds conforming precisely to the doctrine of defi- 
nite and multiple proportions, as formerly explained. The 
reason Avhy so large a number as 200 is taken for the equi- 
valent of mercury, and some other metals, will be understood, 
when it is recollected, that the data from which all the pro- 
portional numbers are estimated, is the proportions of hydro- 
gen and oxygen forming water. The proportion of oxygen 
in this compound being 8, and this number for oxygen being 
fixed, that for mercury is 200, because it is found by experi- 
ment, that these are the smallest proportions in which thesf 
wo bodies combine. 

MERCURY AND CHLORINE. 

Protochloride of Mercury — 236. 
I p. Mercury 200+1 p. Chlorine 36. 
Calo7iiel. 
When chlorine, a gas formerly described, is brought in 
contact with mercury, at common temperatures, a combina- 
tion takes place between them, amounting to one proportion 
of each, forming a protochloride of the metal. This, how- 
ever is not the common method of preparing calomel ; the 



What is the composition of peroxide of mercury 1 By what simple process is it ob 
tained 1 How may this oxide be decomposed? What is the use of red precipitate ? Ei 
plain tlM ^e^son why the combining number for mercury is 200. 



MERCURY. 207 

two constituents being more conveniently combined in their 
proper proportions, by mixing the bichloride of this metal 
with an additional quantity of mercury. The bichloride of 
mercury contains, as its name signifies, two proportions of 
chlorine and one of the metal. This compound is known un- 
der the name of corrosive sublimate. It contains mercury 200, 
and chlorine 72 parts by weight. When this salt is triturated 
with mercury, the metal absorbs a part of the chlorine, and 
the whole is converted into a protochloride, or calomel. The 
proportions are 272 parts, or 1 equivalent of the corrosive 
sublimate, and 200 parts, or 1 equivalent of the mercury. 
This process affords a beautiful illustration of the truth of the 
doctrine of definite proportions ; for when these equivalents 
are mixed in a mortar, and then sublimed by heat, 36 parts, 
or 1 proportion of the chlorine is transferred from the bi- 
chloride to the metallic mercury, thus converting the whole 
into 472 parts of protochloride of mercury, or calomel. 

This process also shows, in a striking manner, the effects 
of different proportions of the same principles, on the quali- 
ties of bodies. Corrosive sublimate is one of the most active 
and virulent of all metallic poisons, and in doses of only a few 
grains, occasions the most agonizing symptoms, which com- 
monly end in death. But calomel is a mild and safe medi- 
cine, which maybe taken in doses of 60, or even 100 grains, 
without injury. And yet the only chemical difference between 
these two substances is, that the calomel is a compound of 1 
atom of chlorine combined with one of mercury, while corro- 
sive sublimate consists of 2 atoms of the first and 1 of the 
metal. 

MERCURY AND SULPHUR. 

Sulphur et of Mercury — 216. 
1 p. Mercury 200+1 p. Sulphur 16. 
Cinnaba^ . 
Cinnabar is prepared by fusing mercury and sulphur to- 
gether, and afterwards subliming the compound. When this 
compound is reduced to a fine powder, it forms the well 



What is said of the combination between mercurv sma the gas chbms. Ht common 
temperatures'? What comm.on name has the protochioriae of mercury 1 How does tho 
protochloride differ from the bichloride of mercury I "WTiat is the common name for the 
bichloride of mercury 1 What is the common mode of making calomel 1 What pro- 
portions of corrosive sublimate and mercury com ome and form calomei'? Wha^ two 
principles are strikingly illustrated by this combination What is the composition of 
sulphuret of mercury 7 



208 SILVER. jg 

known pigment vermilion. Cinnabar occurs in nature, la^™ 
large quantities, and is the substance, as already stated, from 
which mercury is chiefly obtained. 

SILVER 110. 

Silver is found native in small quantities. It also occurs 
mixed with several other metals, as copper, antimony, arse- 
nic, and sometimes with gold, but is chiefly found in combi- ^ 
nation with sulphur, forming a sulphur et of silver. ,|| 

This metal, when pure, admits of a lustre only inferior to 
that of polished steel. Its specific gravity is 11, being about 
half that of platina. In malleability and ductility it excels 
all the other metals except gold and platina. 

Silver is fused by the heat of a common furnace, and by 
a long continued and high degree of heat it may be volatili- 
zed, or turned into vapor. By slow cooling, this metal may 
be obtained in regular crystals. It is not oxidated by expo- 
sure to the combined action of heat and moisture, but is 
readily tarnished by sulphureous vapor. Sulphuric acid dis- 
solves this metal, when assisted by heat, but its proper solvent 
us nitric acid, with which it readily combines, and ^vhen the 
solution is evaporated, forms nitrate of silver, a substance 
known under the name of lunar caustic. 

Silver is precipitated from its solutions, by several of the 
'^ikex metals, in its metallic form. This happens when any 
other metal, having a stronger affinity for oxygen than silver, 
is placed in a solution of this metal. 

If a quantity of nitrate of silver, or lunar caustic, be dis- 
solved in Avater, and a slip of clean polished copper be dip- 
ped into it, the copper will be covered with a coat of silver. 

Diana^s silver tree is made by precipitating silver from its 
solution by means of mercury. This interesting experiment 
may be performed in the following manner. Mix together 
six parts of a solution of nitrate of silver, and four parts oi 
a solution of nitrate of mercurj^ both completely saturated. 
Add a small quantity of rain w^ater, and put the mixture into 



What is the more common name for this compound 7 What is vermilion t In what 
Btates does silver occur? What is the substances with which it is chiefly found combined ^ 
What is its specific gravity % What is said of its malleability and ductility 1 How mav 
silver be obtained in crystals 1 What vapor readily tarnishes silver 1 What is the pro- 
per solvent of this metal 7 What is the salt formed when silver is dissolved in nitric 
acid 7 How is lunar caustic formed? How may silver be precipitated in its metallic 
form 1 What is the process for forming Diana's silver tree 7 



SILVER. 209 

a glass decanter, containing six parts of amalgam, made af 
seven parts of mercury, by weight, and six parts of silver leaf. 
In the course of some hours, there will appear small shining 
scales of metallic silver on the amalgam, which will increase, 
and shoot out in the form of a silver tree, producing a very 
beautiful appearance. 

Silvering powder may be prepared in the following man- 
ner. Precipitate silver from its solution in nitric acid, by 
dropping into it some plates of clean copper. Take 20 
grains of this powder, and mix with it two drachms of cream 
of tar tar, the same quantity of common salt, and half a 
drachm of alum. These articles must be finely pulverized, 
and intimately mixed in a mortar. If a little of this powder 
be moistened, and rubbed on a clean surface of brass or cop- 
per, the silver will be precipitated, and the surface of the 
metal will be covered with it. In this way the silvering of 
candlesticks, or other articles, where it is worn off, may be 
replaced. The addition of the other articles to the precipi- 
tated silver, probably serves no other purpose than to keep 
the surface of the brass perfectly clean, and free from oxide, 
as the powder is rubbed on. 

Silver may also be precipitated on ivory, and then revived 
by the action of solar light. Into a dilute solution of nitrate 
of silver immerse a slip of polished ivory, and let it remain 
until it acquires a yellovv^ color, then place it in a tumbler of 
pure water, and expose it to the direct rays of the sun for a 
few hours, or until it turns black. If now, it be gently rub- 
bed, the surface will be changed into a bright metallic one, 
and the slip of ivory will, in appearance, be transmuted 
into one of silver. This change is caused by the deoxidizing 
power of the solar rays, in consequence of which, the oxy- 
gen is separated from the silver, and the metal reduced to its 
former state. 

A very useful solvent of silver is made by dissolving one 
part of nitre with about eight parts of strong sulphuric acid. 
This solvent, when heated to about the temperature of boil- 
ing water, will dissolve silver, without acting on gold, copper. 



How may silvering powder be prepared 7 What is the use of the silvering powder? 
Of what use are the other ingredients in this powder besides the precipitated silver * 
What is the process for silvering ivory 1 How do you account for the return of the sil- 
ver to its metallic state by being placed in the sun ? Wliat is the composition of a solvem 
for silver, which doe? not act upKDn other metals? 

18* 



210 GOLD. 

lead, or iron, and hence may be conveniently used to extract 
the silver from old plated goods, &/C. 

The combining number for silver is 110, it having been 
found that the oxide of this metal contains 110 silver, and 8 
oxygen. 

The sulphuret of silver is composed of 110 of the metal, 
and 16 sulphur. 

GOLD— 200. 

This well known precious metal is found only in the me- 
tallic state, either alone, or mixed with other metals. Con- 
sequently, there is no such thing as an ore of gold. Gold is 
sometimes found disseminated in rocks, but always in its 
metallic state, and never mineralized by sulphur, oxygen, or 
any other substance. Its specific gravity is 19. It is the 
most malleable of all the metals, and in ductility is only ex- 
celled by platina. 

The extent to which a given portion of this metal may be 
spread, and still continue a perfectly unbroken surface, is truly 
astonishing. A single grain of the best wrought gold leaf is 
found to cover fifty-six square inches, and it v/ould take near- 
ly 282,000 such leaves to make an inch in thickness. This, 
however, is not the utmost limit to which its tenuity may be 
extended, for the wire used by lace makers is drawn from an 
ingot of silver gilded with this leaf, and from the diameter of 
the ingot, compared with that of the wire, it has been found 
that the covering of gold on the latter is only a twelfth part 
of the thickness of gold leaf Supposing the leaf, when first 
placed on the silver, to have been the 30 thousandth part of 
an inch in thickness, the covering on the wire would require 
360,000 times its own thickness to make an inch ; and still 
this covering is so entire that, even with a microscope, the 
silver is not to be seen. 

Gold is the only metal which can be made so thin as to 
transmit the ia,js of light, and the rays so transmitted, instead 
of being of the same color with the metal, are green. 

This metal, w-.en pure, is not oxidated, or otherwise alter- 
ed, by being kept in fusion, in the highest heat of a furnace 



What is the equivalent number for silver? In what state is gold always found ? Are 
there any ores of gold ? What is the specific gravity of gold 7 What illustrations are 
given of the malleability of gold? What is said of tlie thickness of this metal on the 
wire uyed by lace makers ? What is said of the light seen through gold leaf? How i« 
g.old affected by continued fusion at the highest degrees of heat 7 



GOLD. 211 

for any length of time. Sulphuric, nitric, or muriatic acid, 
do not alone produce the least action on gold ; but when two 
parts of nitric and one of muriatic acid are mixed, forming 
aqua regia, the mixture dissolves this metal wath facility. 
Put some nitric acid into one vessel, and some muriatic acia 
into another, and throw a little gold leaf into each. Not the 
least effect on either will be produced ; but if the contents of 
one vessel be poured into the other, immediate action will 
ensue, and the metal will soon be dissolved. 

The solution of gold is decomposed by many substances 
which have a stronger attraction for oxygen than this metal 
has, and by absorbing the oxygen, restores the gold to its 
metallic state. 

If a piece of ribbon, or other substance, be moistened with 
some dilute solution of gold, and exposed to the action of a 
current of hydrogen, the gold wdll be revived, and the rib- 
bon, or other substance, will be covered w^th a film of gold. 
By means of a camel hair pencil, the solution maybe applied 
to the ribbon in regular figures, and as the appearance of the 
ribbon is not changed by the application, until the hydrogen 
is throv»ai upon it, a striking experiment may be made in this 
way. The hydrogen must be applied w^hile the ribbon is 
moist, and may be blow^n on, through a tube attached to a 
bladder containing it. 

Sulphuric ether precipitates gold, but instantly dissolves 
the precipitate, forming an etherial solution of the metal. 
This solution is sometimes employed to gild lancets, scissors, 
and other instruments, in order to preserve them from rust. 
This is readily done by the following method. Into a given 
quantity, say an ounce of the nitro-muriatic solution of gold, 
pour twice as m^uch sulphuric ether ; shake the vessel, and let 
it stand two or three minutes, and then pour into another ves- 
sel about one third of the mixture. The acid does not mix 
with the ether, but settles to the bottom of the vessel, leaving 
the ether in possession of the gold on its surface ; the por- 
tion decanted into the other vessel, therefore, is an etherial 
solution of gold. Any perfectly clean and polished steel m- 
strument, will be covered with a coat of gold, if dipped for a 
moment into this solution. When taken from the ether, it 



Wliat acids dissolve gold 1 How may the solutions of gold be decomposed ? In what 
manner may figures of gold be made on ribbon 1 What are the directions for making 
an etherial solution of gold 7 In what manner may steel instruments be gilded with sui 
. etherial solution of g-old ? 



212 PLATINUM. 

should be instantly plunged into pure water, to wash off any 
particles of acid, which may be retained in the solution. The 
instrument may afterwards be burnished, when it will have 
all the appearance of the best gilding. 

In this case the gold appears to be in its metallic state, and 
to be retained on the surface of the steel by the attraction oi 
cohesion, while the ether evaporates. 

PLATINUM 96. 

Platinum is a white metal, resembling silver in color, but 
a little darker. It is the heaviest of all known bodies, having 
a specific gravity of 22. 

This metal comes chiefly from several parts of South Ame- 
rica, where it is found in small grains, or scales, exceedingly 
heavy, and nearly the color of wrought iron. In this state 
it is alloyed by several other metals, and requires to be puri- 
fied before it is malleable. It was first discovered in 1741, 
but has not been applied to any considerable use until within 
the last twenty years. This metal has lately been discovered 
in considerable quantities in Russia, and is employed for the 
purposes of coin, for which it is well adapted. 

Platina, like iron, may be welded, and like gold, suffers no 
change from the combined agencies of air and moisture, or 
hy long continued heat. For many purposes, therefore, it is 
the most valuable of all the metals. 

This metal is so difficult of fusion, as to undergo the great- 
est heat of a smith's forge without the least change. None 
of the acids act on it, except the nitro-muriatic, the solvent of 
gold. 

Platinum is purified and obtained in a malleable state by 
dissolving the grains in 8 times their weight of aqua regia, 
assisted by heat. The acid only dissolves the platinum, leaving 
the iridium and osmium, the metals with which it is alloyed, in 
the form of a precipitate at the bottom of the vessel. The acid 
solution is then evaporated, and the metal precipitated by mu- 
riate of ammonia. The precipitate thus obtained, is heated 
in a crucible, lined with a mixture of clay and charcoal, to 
the utmost degree that can be attained in a blast furnace, 



What is the color of platinum? What is its specific gravity? Is there any knoAvn 
•>ody of greater specific gravity than platina ? In what countries is platina found ? Wliea 
\ as this metal discovered ? In what respect docs olatina possess the property of iron 1 
li.» what respect is this metal like gold 7 Vv'hat is said of ihp action of heat^ and of the 
ac"' %, on platinum? 



I'LATINUM. 213 

when tlie ammonia and acid are driven off, and tlie fused 
metal falls to the bottom of the crucible. It is afterwards 
several times healed, and hammered, when it becomes both 
ductile and iTialleable. In small quantities, this metal may 
be fused by the compound blowpipe. 

Platinum combines with many of the other metals by fu- 
sion, and forms alloys which possess various properties, som« 
of which are useful. 

Copper, when alloyed with from one sixth to one twenty- 
fifth part of platina, becomes of a golden color, is much less 
readily oxidated than before, and receives a fine polish. 

With iron, platina is said to form a compound highly es- 
teemed by the Spaniards, for the purpose of making gun bar- 
rels, which are stronger, and less apt to rust, than iron alone. 

From its infosibility, and the difficulty with which it is 
oxidated, this metal is highly useful in the arts, and particu- 
larly for making various chemical and philosophical instru- 
ments. 

Retorts of platina are now employed instead of lead, for 
the distillation of sulphuric acid. Being acted on neither by 
heat, nor any single acid, such vessels will probably last even 
for centuries without repair. Their expense would, however, 
often be an objection to their use. In Mr. Tennant's great 
works for the manufacture of bleaching salt, at Glasgow, it 
is said there are nine pladna retorts, which cost about 2,500 
dollars each. 

Platina is the slowest, or most imperfect conductor of heat, 
among the metals, and from this quality, together with that 
of sustaining a high degree of heat without oxidation, it may 
be employed to construct the aphlogistic or flameless lamp. 

This curious lamp retains a coil of platina wire constant- 
ly at a white heat, without either flama or smoke. It may be 
constructed in the following manner : 

The platina wixe to be used for this purpose is about the 
thickness of card, or brass wire, No. 26. If larger, the heat 
is carried off too fast, and the ignition ceases, and if much 
finer, it does not retain sufficient heat to keep up the evapo- 
ration of the alcohol, by the conibu;Stion of which, the heat 
of the wire is maintained. 



How is this nietal purified and rendered niaiieable 7 Does platinum form alloys with 
the other metals by fusion 1 What alloys of platina are mentioned as being useful 1 For 
what useful purposes has the pure metal been employed 1 Is platina a good or bad coa- 
^cior of heat 1 What ie the aphlogistic or flameless Jamp 1 



214 



PLATINUM. 




Such a piece of wire, six or eight inches long, a piece o: 
glass tube, and a low vial, are the chief materials for the con' 
struction of this lamp. 

The coil A, Fig. 62, is made 
by winding the wdre round a 
piece of w^ood cut of the pro- 
per size and shape. The size 
is determined by that of the 
aperture of the tube, allowing 
for the diameter of the wire. 
Its shape is a little conical, or 
tapering upwards. In winding 
the coil, it is best that the turns 
of the wire should come in con- 
tact, and afterwards be gently 
extended, so as to comeasnear- 
^ ly as possible to each other with- 
out touching. The diameter 
of the coil may be one fourth, 
one sixth 



^li^„ , ,,, , , 

^I|^M__ 

^JMMH?mH!iy!i«B!iiKiHEiaii53HiHEiiiip.!!H!5!SjQj, One sixth of an inch, and 

its length half an inch, containing twenty or thirty turns of 
the wire. 

J5 is a glass tube three or four inches long, containing the 
cotton w4ck by which the alcohol is carried up to the wire. 
The wick passes about half way through the coil. 

C is the body of the lamp w^hich contains the alcohol. It 
is a low vial, or glass inkstand, capable of holding two or 
three ounces. The glass tube passes through a cork, and 
dips into the fluid. D is a small tube through w^hich the al- 
cohol is poured. This must be stopped to prevent evapora- 
tion. 

When the lamp is thus prepared and filled with alcohol, 
the fluid is set on fire by holding the platina wire in the 
flame of a candle, and after a few minutes, or when the coil 
becomes red hot, the flame is blowm out, and if every thing is 
properly adjusted, the w^ire will remain red hot as long as the 
vial contains alcohol. 

The following appear to be the causes of the permanent 
ignition of the wire. Alcohol, when in the state of vapor, 
combines with oxygen with facility. The temperature of the 
wire is raised by the flame of the candle to about 1000 de- 

Explain Fig. 62, and describe the construction of the flameless lamp. With what fluid 
IS the lamp filled 1 How is it lighted ] Explain the principles which cause the perma* 
oent ignition of the platina wire. 



.1 



MEl'ALS. 215 

grees, the point at which alcohol combines with oxygen, or is 
combustible. When this is once effected, the caloric extrica- 
ted by the combustion of the alcohol is sufficient to keep the 
-coil at a red heat, w^hich again is the temperature at which 
alcohol is combustible, so that one portion of alcohol, by the 
absorption of oxygen, and the consequent evolution of heat, 
prepares the wire to effect the combustion of another portion, 
and as the alcohol rises in a constant stream of vapor, so the 
ignition is constant. 

In cases where a light might be suddenly wanted, this 
lamp is highly convenient, for by touching a match to the 
coil, and then to the wick of a candle, a light is immediately 
obtained. 

Platinum combines with oxygen in two proportions, form- 
ing the 

Platinum. Oxygen. 

Protoxide, composed of 96 and 8, 
Peroxide, do. 96 '* 16. 

PALLADIUM. RHODIUM. IRIDIUM AND OSIMUM. 

These four metals were found, by Dr. Wollaston and Mr 
Tennant, among the grains of platina brought from South 
America. 

Palladium. This metal resembles platina in color, but is 
not quite so brilliant. It is malleable and ductile, and its spe- 
cific gravity is about 11.5. Its fusing point is between those 
of gold and platinum. It is soluble in the sulphuric, nitric, 
or muriatic acids. Neither the metal nor its oxides have 
been applied to any use. Its atomic weight, or combining 
number, is 56. 

Rhodium, This metal is hard, brittle, and its specific gra- 
vity is about 11. It is not acted on by any of the acids, 
not even the nitromuriatic, except when alloyed by other 
metals. It requires the strongest heat of a wind furnace for 
its fusion, and when pure is of a white color, and brilliant 
lustre. Its solution in nitromuriatic acid is of a rose red 



What is the use of the aphlogistic lamp 1 What is the equivalent number for plati- 
num? What are the names of the oxides of this metal, and what the proportions of 
tlieir elements 7 Where were the metals palladium, rhodium, iridium, and osmium, 
first discovered ? What is the color, and what are the properties of palladium ? What 
Is the combining number for palladium ? What is the specific gravity of rhodium 1 
WTiat is the wlor, and what are the properties of rhodiun* ? 



216 METAIS. 

color, and hence the name rhodium, from a Greek word sig 
nifying a rose. 

The atomic weight, or combining numberof rhodium, is 44. 

Iridium and Osmium. When platina is dissolved in aqua 
regia, there remains a black heavy powder, at the bottom, of 
the vessel, which consists of a mixture of iridium and osmi- 
um. Iridium has been fused, only by the heat of an im.- 
mense galvanic battery. The metal is v/hite, and of a spe- 
cific gravity next to that of platinum, being 18.5. It is dis- 
solved with great difficulty in any of the acids ; has been 
obtained only in small quantities, and is of no use. 

Osmium is of a dark gray or blue color, and capable of 
supporting a white heat, without being volatilized, or fused. 
The oxide of this metal is precipitated in its metallic state 
by copper and several of the other metals, ??!nd the precipitate 
being agitated with mercury, an amalgam is formed, which 
being heated, the mercury is driven off, and the osmium in a 
pure state remains. In this manner is the metal obtained. 
It is of no use, and has been procured only in small quan- 
tities. 

CLASS 11 

Metals, the oxides of which are not reducible to the me 
iallic state by heat alone. 

Order 1. Metals which decompose water at common tem- 
peratures. These arej 

Potassium, Lithium, Strontium, 

Sodium, Barium, Calcium. 

These metals attract oxygen with the most intense degree 
of force. They absorb it from the atmosphere, and even 
decompose water, by combining with its oxygen, at common 
temperatures. Such is the force by which they hold this 
principle, that their oxides had resisted all attempts to decom- 
pose them, until the discovery of galvanism placed in the 
hands of men a more powerful decomposing agent than was 



From ^hat circumstance is the name of this metal deriyed ? What is the equivalent 
number of rhodium? How are iridium and osmium obtained 7 What is the specific 
gravity of iridium 1 What is said of its fusibility, and solution in acids 1 What are tlie 
properties of osmium 1 How is osmium obtained in its pure state ? What is the defini- 
tion of class II. ? What is the definition of order 1st, of this class 7 What are the names 
of the metals t>aIonging to this order 1 What is said of the intense degree of force with 
which theec xnetals attract oxygen? By what decomposing agent were tJie alkalies 
shown to be t>ie oxides of metals 7 



POTASSIUM. 217 

before kno\Mi. By means of the most intense electrical re- 
pulsion, the alkalies, before considered as simple bodies, were 
sho^ATi to be the oxides of metals. After the secret of their 
composition was known, chemists de^dsed other and less ex- 
pensive means of effecting their decompositions, so that at the 
present time, sodium and potassium, at first the most expen 
sive of all substances, are within the means of any one 

POTASSIUM — 40. 

If a small piece of pure potash, slightly moistened, be put 
oetween two plates of platinum connected with the poles oi 
a galvanic battery of 200 double plates, the alkali will soop 
be fused and decomposed. Oxygen will separate at the posi- 
tive pole, and small metallic globules, like quicksilver, will 
appear at the negative pole. In this manner, Sir H. Da-^y 
first determined the composition of potash, and separated its 
elements. Potash, therefore, is a compound consisting of a 
metal csWei potassiujn, united to oxA'gen. 

By this process the metal can be obtained only in minute 
quantities : but chemists, now understanding that to obtain 
potassium in any quantity, only required that the oxygen 
should be separated from the potash, soon found more ready 
means of performing the experiment. The following is the 
method first employed by Thenar d : 

A clean and perfectly sound gun-barrel is pro^-ided, and 
bent in the manner shown in Fig. 63, and covered with an 
infusible lute beiween the letters O and E, Fig. 1. The in- 
ferior of the luted part is filled with clean iron turnings, and 
pieces of fused potash are placed loosely in the part between 
E and C. 

What is the process by which Sir H, Davy decomposed potash? 

19 



ei8 




A, A, is a copper tube and small receiver, adapted to the 
extremity of the barrel O, and to each other, by grinding. 
This apparatus is then transferred to a furnace, arranged as 
shown by Fig. 2. At each end of the barrel are the glass 
tubes X and T, dipped into cups of mercury, so as to let the 
air from the barrel escape, as it is rarefied by the heat, and 
at the same time prevent its return. The furnace is supplied 
with air by a double bellows entermg at B, and a small wire 
basket, G^is suspended in the space between E, and C. The 
part of the barrel in the furnace is now raised to a white heat. 
'^^4 the escape of air by the tube X, shows that all is tight. 
e»ome burning charcoal is now placed in the end E, of the 
basket, which causes a portion of the potash to liquefy and 
fall into the lower part of the gun-barrel, among the iron 
turnings. Hydrogen gas instantly escapes at the tube X, in 
consequence of the decomposition of the water contained in 
the potash, by the heated iron. The copper tubes, A, A, 
must now be kept cool by wet cloths. When the evolution 
of gas ceases, fresh charcoal is placed under the potash, and 
so on till the whole has passed down. If too much potash 
be allowed to fall do^vn at once, the extrication of hydrogen 
at X, will be violent, and should be avoided. If the space 

Describe Fig. 63, and explain the method of decomposing potash by means of iroTi 
tumiii^a sand hem. 



POTAiiSIUM. 219 

between A and O, should become stopped by potassium, the 
g-as will issue at the tube T, and then some burning charcoal 
must be placed between A and O, which will remove the 
obstruction. 

When all the potash has been fused and made to pass 
among the iron turnings, the process is finished, and then 
the tubes X and T, must be removed, and the ends of the 
barrel instantly stopped with corks until the apparatus has 
cooled. The barrel is then carefully removed, and a littl 
naphtha suffered to run through it, by which the potassium is 
coated and thus preserved from the contact of air, while pour- 
ing out of the barrel. The potassium Ls found in globules 
in the tube and receiver, A, A. 

The success of this process is certain, if the heat is suffi- 
cient ; but the barrel, if not carefully covered with lute, is apt 
to melt, when most, if not all, the potassium will be lost. 

In this process, the decomposition of the potash is effected 
by the iron turnings, which at a high heat have so strong an 
attraction for oxygen, as to absorb it from the potassium, and 
as tne iron combines with the oxygen, the potassium is left 
in its pure state. 

Potassium is solid at ordinary temperatures, but becomes 
fluid at 150^, and then appears like mercury. It is perfectly 
opaque, and a good conductor of electricity and caloric. At 
ihe temperature of 50°, it is soft like wax, and yields to the 
pressure of the fingers. In this state it resembles an amal- 
gam of mercury and tin. Its specific gravity is 0.865, water 
being 1.000. 

The most prominent chemical property of this metal is its 
extreme avidity for oxygen. When exposed to the air, it 
oxidizes rapidly, and when thrown on water it decomposes 
that fluid, by absorbing its oxygen with such rapidity as to 
set itself on fire, and burns with a white flame, and great evo- 
lution of heat, while swimming on its surface. 



Wliat is the condition on which it is said this experiment will certainly succeed 7 
What is the principle on which the decomposition of the potash is effected by means of 
iron turnings and heat'? What is the appearance of potassium 7 Is it a conductor 
of caloric and electricity! At what temperature does it become fluid, and at what tem- 
perature is it solid ? What is the specific gravity of this metal 1 What phenomena are 
produced when potassium is thrown on water ? 



220 POTASSIUM AND OXYGEN. 

POTASSIUM AND OXYGEN. 

Protoxide of Potassium — 48. 
1 p. Potassium 40+1 p. Oxygen 8. 
Potash, 

Potassium combines with oxygen in two propoiitions, form 
ing the protoxide, and peroxide of potassium. The first, which 
IS common potash, is formed whenever potassium is put into 
water, or exposed to dry air, or oxygen gas. 

The proportion of oxygen which this metal absorbs, to 
convert it into potash, is readily ascertained by the volume 
of hydrogen liberated when it acts on water. For, when 
potassium is plunged at once under that fluid, it is oxidized 
without the evolution of light or heat, and it is found that 
each grain of the metal so placed, separates 106 cubic inches 
of hydrogen gas. Now, by knowing previously what are the 
relative volumes and weight of hydrogen and oxygen com- 
posing water, it is easy to calculate the exact quantity of oxy- 
gen absorbed, by the above data. 

Thus, Sir H. Davy found that 40 grains of this metal de- 
composes precisely 9 grains of water. Now as 9 grains of 
water is composed of 1 grain of hydrogen, and 8 oxygen, so 
40 parts of potassium combines with 8 parts of oxygen, to 
form oxide of potassium, or potash. Potash is therefore com- 
posed of 

Potassium 40 or one atom. 
Oxygen 8 or one atom. 

48 combining number for potash. 

When potassium is allowed to absorb oxygen in the open 

air, or when plunged under water, it combines Avith only one 

proportion of oxygen, as above stated. But when this metal 

burns in the open air, or in oxygen gas, it is converted into 



In how many proportions does potassium combine with oxygen 7 What common 
substance is formed when potassium is exposed to the air 1 When potassium is plunged 
under water, how is it ascertained what quantity of oxygen it absorbs ? Suppose 40 
grains of potassium decompose 9 grains of water, how does it appear in what proportion 
potassium and oxygen combine? \Vhat is the equivalent number for potash ? Whec 
potassium is burned in the oj^en air, or in oxygen gas, what proportion of oxygen do» 
it absorb 1 



SODIUM. 224 

an oran je colored substance, which is the peroxide of potaa- 
8ium. This is composed of 

Potassium 40 or one atom. 
Oxygen 24 or three atoms. 

The potash of commerce is obtained from the ley of wood 
ishes, boiled down in pots, and hence the name potash. It 
is chiefly used in the manufacture of soap and glass. For 
the former purpose, the ley itself is often employed, and is 
better than the solid potash, dissolved in water, since the pot- 
ash soon absorbs carbonic acid, and then its quality for soap 
making is in a great measure destroyed. From this circum- 
stance, it is, that soap makers mix with their ley a quantity of 
newly burned quicklime, which renders the solution of potash 
caustic, by absorbing from it the carbonic acid, with which it 
has combined. 

Soft soap only can be made from potash, while hard soap 
s made from soda. 

Common green glass is made by fusing sand and wood 
ashes together, by means of an intense heat, produced by the 
combustion of dried wood, in a blast furnace. Flint glass, 
which is perfectly white and transparent, is made by fusing 
together a quantity of potash and white sand, or ground 
quartz, to which are added a proportion of lead, and a little 
manganese. 

Salt of tartar, salt of wormwood, pearl-ash, and carbonate 
of potash, are only difl!erent names for the same article, some 
of which are more pure than others. 

SODIUM 24. 

By the same process which showed potash to be a com- 
pound body, soda was also found to be of the same nature. 
Although first procured by means of galvanism, it may be 
obtained by precisely the same method as that described for 



What is the oxide called which is so formed 'I How Is the potash of commerce pro- 
^ured 7 In what manufactures is the article chiefly employed 7 What is the use of carbo- 
nate of lime in soap malcing ? How do the soaps made frwn potash and soda differ? What 
are the materials for making green glass 1 What are the materials for making flint 
glass 7 What other names are applied to potash 7 What is the process of decomposing 
ecla, and obtaining the metal sodium? 

19* 



222 SODIUM AKD OXYOfiN. 

the production of potassium, only placing soda in the gun 
carrel, instead of potash. 

Sodium has a strong metallic lustre, similar to that of sil- 
ver. It is a little less fusible than potassium, not becoming 
perfectly fluid until it has acquired the temperature of nearly 
200°. Its specific gravity is somewhat greater than that of 
potassium, being 0.972. When thrown on water it pioduces 
a violent effervescence, but does not inflame like potassium. 
The water is decomposed by its action, hydrogen escapes, 
and there remains a solution of soda in the water. Like po 
tassium, it must be preserved in a vial covered by na'phtha, a 
substance which contains no oxygen. 

SODIUM AND OXYGEN.. 

Protoxide of Sodium— ^32. 
1 p. Soda 24+1 p. Oxygen 8. 

Soda. 

When the metallic base of soda is burned in dry atmos-^ 
pheric air, protoxide of sodium, or soda, is formed. The 
same compound is formed when sodium is thrown into water, 
and the composition may therefore be determined in the man- 
ner already described for potassium. From such an experi- 
ment it has been found that soda is composed of 

Sodium 1 equivalent 24 

Oxygen 1 do. 8 

82 equivalent of soda. 

The peroxide of soda is composed of the same equivalent 
of sodium, with two equivalents of oxygen. Sodium 24, oxy 
gen 16 — 40. 

Soda is readily distinguished from other alkalies by the 
following characters. With muriatic acid it forms the com- 
mon table salt, with the taste of which, every one is familiar. 
With sulphuric acid it forms Glauber's salt, or sulphate of 



What is the appearance of sodium ? In what respects does this metal differ from po 
tassium T What is the effect when sodium is thrown upon water? How is the metal 
preserved 1 ^Vhat compound is formed when sodium is burned in atmospheric air, oi 
thrown into water 1 What is the composition of protoxide of sodium, or soda 1 What 
w the equivalent number for soda 1 How is soda distinguished from the other alkalies 1 



SODIUM AND CHLORINE. 22S 

Soda All the salts of soda are soluble in water, and are not 
precipitated by any other substances. 

S0DIUM AND CHL#RINE. 

Chloride of Sodium — 60. 

1 p. Sodium 24+1 p. Chlorine 36. 

Covimon Salt. 

When sodium is exposed to chlorine, or is heated in muri 
atic acid gas, the salt is formed j lately known under the 
name of muriate of soda, or common salt. This is an abun« 
dant product of nature, and exists, ready formed, in Spain, 
England, Poland, and other countries, in large quantities. 
In these countries it is dug out of the earth, and is known 
by the name of rock salt. Sea water and certain springs 
also contain this salt in solution. 

When common salt is dissolved in water, and the solution 
is evaporated rapidly, it crystallizes in the form of hollow 
four-sided pyramids ; but if allow^ed to evaporate spontaneous- 
ly, it occurs in regular cubes. Thus, the crystals show in 
what manner the salt has been manufactured. In England, 
vast quantities of salt are annually raised from the mineSj 
chiefly of Cheshire, and purified for sale. The impurities 
consist chiefly of clay and oxide of iron, besides which, it 
contains various proportions of sulphate of magnesia, or Ep- 
som salt, sulphate of lime, and muriate of lime. It is purified 
by bemg dissolved in sea-water, and subsequ^iTtly evaporated. 
Formerly, all the English salt was evaporatea by artificial 
heat, the brine being boiled until it was ready to shoot into 
-crystals. Its crystals w^ere, therefore, always in the form of 
hollow pyramids. But it has been supposed, by victuallers 
and others, that this salt is far less efficacious, as a preserver 
of animal food, than that prepared by the spontaneous evapo- 
ration of sea- water in hot climates. Hence, salt from the West 
Indies, which is crystallized in solid cubes, has been preferred 
ft^r curing provisions for long voyages, or for summer use. 



VVTiat is cliloride of sodium ? What the sources of common salt 7 When a solution 
of common salt is evaporated rapidly, what is the form of its crystals 1 When evapora- 
ted slowly, in what form are the crystals 1 Where are the salt mines of England 1 
What impurities exist in the Cheshire rock salt 7 How is this salt purifiea ? Wliy were 
the crystals of this salt always in the form of hollow pyramids "^ What salt was formerly 
supposed b€»t for the preservation of animal substances 7 



22t LITHIUM. 

In this country, although immense quantities of common salt 
are manufactured, by the evaporation of water from salt 
springs and from the sea, and a sufficient supply for our con 
sumption might be made, yet we annually import large quan- 
tities from the West Indies, there having been, until lately, an 
opinion that no other kind of salt would preserve animal sub- 
stances through the hot season. 

Dr. Henry, for the purpose of ascertaining the difference 
between English salt, crystallized by heat, and that from the 
West Indies, crystallized by spontaneous evaporation, ana- 
lyzed many specimens of each. The result showed the pre- 
sence of sulphate of magnesia and sulphate of lime in both, but 
the difference in the quantity of muriate of soda, in several 
specimens of each kind, was so trifling, as to make no possi- 
ble difference in respect to their preserving qualities. It is 
presumed, therefore, that the prejudices in favor of foreign 
salt ought to be discarded as imaginary, and that equal 
weights of fine or coarse salt, w^hether made by artificial or 
spontaneous evaporation, are equally efficacious for all pur- 
poses. 

Common salt contains no water of crystallization, but de- 
cripitates remarkably when heated, owing to the conversion 
of the water into steam, which is mechanically confined with- 
in its crystals. Its solubility is not, like most other salts, in- 
creased by heat, and it requires two and a half times its 
weight of water for solution, whether hot or cold. 

LITHIUM 18. 

Lithia is an alkaline substance, discovered by M. Arfwed- 
son, a Swedish chemist, in 1818. It exists in the minerals 
called sjpodumene, and lepidolite, and also in some varieties oj 
mica. 

This alkali is distinguished from potash and soda, by its 
power of neutralizing larger quantities of the different acids, 
and by its action on platinum, when melted on that metal. 

In respect to its metallic base, called lithium, Sir H. Davy 
succeeded, by means of galvanism, in obtaining a white metal 



What is said of the real difference between salt made by rapid or slow evaporation t 
Does common salt contain any water of crystallization 1 Why does common salt decri- 
pitate, 01 fly in pieces, when thrown upon a fire? Is the solubility of this salt increased 
by heat 1 What quantity of water does it require for solution ] What is lithia 7 In what 
wiinerals is this alkali found ) How is lithia distinguished from potash and soda 1 



METALS. 225 

Horn lithia, similar in appearance to sodium, but it was oxi- 
dized so rapidly, and reconverted into the alkali, that it could 
not be collected. 

From the experiments of several chemists on the sulphate 
of lithia, it is inferred that the alkali, lithia, is composed of 
the metal lithium 10, combined with oxygen 8, making the 
combining number for lithia 18. 

Lithia has been procured only in very small quantities, 
and has never been applied to any useful purpose. 

BARIUM 70. 

There is a substance, called sulphate of harytes, which is 
found abundantly in nature. By the decomposition of this 
substance, an alkaline earth is obtained, called baryta or ha- 
rytes. When barytes, in the form of paste mixed with water, 
is exposed, in contact with mercury, to the action of a power- 
ful galvanic battery, its decomposition is effected, and the 
metal barium, its base, amalgamates with the mercury. The 
amalgam being exposed to heat, the mercury is driven off, 
and pure barium remains. 

The metal thus obtained, is of a dark gray color, with a 
lustre inferior to cast iron. It fuses at a heat below redness, 
and at a red heat is converted into vapor, w^hich acts violently 
upon glass. The specific gravity of barium is four or five 
times that of water. When exposed to the air, it falls into 
a white powder, which is found to be an oxide of barium, or 
bar3rtes. When heated in oxygen, it burns w^ith a deep red 
light, and when throAvn into water, the fluid is decomposed, 
hydrogen being extricated. 

BARIUM AND OXYGEN. 

Protoxide of Barium — 78. 

1 p. Barium 70+1 p. Oxygen 8. 

Barytes. 

When the metal barium, is exposed to the air, it falls into 

a powder, which was formerly called pure barytes, or baryta, 

but which Sir H. Davy has proved by the above stated ex- 



What is known concerning the metallic base of this alkali ^ What are the equivaleni 
numbers of lithium, and lithia 1 How is baryta obtained 1 By what process is barium 
separated from baryta 1 What is the color of barium 1 At what temperature is barium 
fusible'? What is the specific gravity of barium 7 When barium is exposed to the air 
what compound is formed 1 



226 METALS. 



periment, to consist of a metal and oxygen. This substan^'e 
is therefore called oxide of barium. 

Oxide of barium may also be obtained by a different pro- 
cess from that above described, viz. by exposing the carbon- 
ate of baryta to an intense heat, mixed with charcoal. 

The carbonate of barytes is found native in small quantities, 
but may be obtained from the sulphate of barytes by a simple 
process. Mix sulphate of barytes in fine powder, with three 
times its weight of carbonate of potash, (pearlash), and a pro- 
per quantity of water. Let the mixture boil for an hour, now 
and then breaking the lumps into which it is apt to run, with 
a pestle. By this means the two salts will decom.pose each 
other, and there will be formed carbonate of barytes, and sul- 
phate of potash. The carbonate may now be exposed to a 
high heat, or it may be dissolved in nitric acid, and this de- 
composed, which is effected by a moderate heat, when prot- 
oxide of barium, or barj-tes, will be obtained. This substance 
is of a w^hite color, has a sharp caustic taste ; changes vege- 
table blue colors to green ; neutralizes acids, with which it 
forms salts, and is a strong poison. When water is throv.i3 
on it, it falls into fine powder, like quicklime, but with a 
greater evolution of heat. 

Barytes is composed of 

1 equivalent, or atom of barium, 70 

1 do. of oxvsen, 8 



I 



The equivalent combining number for barytes, 78 

Bar}tes is soluble in about twent}' parts of water, at com- 
mon temperatures, and this solution forms a delicate test for 
the presence of carbonic acid. The carbonate of barbies 
being insoluble in water, a white cloud is instantly formed by 
the union. 

STRONTIUM 44. 

The sulphate and carbonate of strontian, or strontia, are 
native salts. They consist of pure strontian, combined Avith J 
sulphuric and carbonic acids. From the sulphate, the car- \ 



When thrown into water, what effects are produced 1 By what process may barium 
oe obtained without the agency of galvanism ? How may carbonate of barytes be ex 
traded from the sulphate 7 What are the properties of barytes, or protoxide of barium] 
Wliat is the composition of barj-tes ■? In what quantity of water is barytes soluble! 
\\Tiy is barytes a test for carbonic acid 1 How is the carbonate of strontian prodoeed 
from the sulphate 1 



METALS. 227 

boi ate may be procured by precisely the same means as al- 
reaay described for bar^-tes, and the pure oxide may also be 
:>6tamed, and the metal strontium separated from it, by the 
&ame process as that described for barytes. 

Strontia resembles bar^-la in most respects. It slakes in 
water, causing- an intense heat, and possesses distinct alkaline 
properties. 

The metal strontium is similar to barium in appearance. 
and when exposed to the air quickly attracts oxygen, and is 
converted into strontia. Perhaps the principal difference be- 
tween these two substances, which has been detected, is their 
different combining proportions with oxygen, and the inertness 
c^f the oxide of strontium on animals. 

The protoxide of strontium connsists of 
Strontium, 1 equivalent 44 
Oxygen, 1 do. 8 

52 

The oxides of barium, as already stated, are strong poi- 
sons, but those of strontium are inert. 

CALCIUM 20. 

When carbonate of lime, or vrhite marble, is exposed to a 
. ed heat, the carbonic acid is expelled, and there remains a 
V\'hite caustic substance, well known under the name of quick- 
lime. When this substance is exposed to the action of galva- 
nism, in the same manner as already described for the decom- 
position of barv^tes, calcium, the metallic base of lime, is sepa- 
rated. This metal is of a whiter color than barium, and has 
a lustre like silver. TV^hen exposed to the air, it absorbs oxy- 
gen, and is converted into quicklime, and when thrown into 
water, the fluid is decomposed, its oxygen being absorbed, 
while hydrogen is given off, and a solution of lime remains 



How is the pure eanh strontia obtained from the carbonate ? By what process is the 
Kx€tal strontium separated from strontia ? What is the appearance of this metal? ^^^lat 
is the composition of strontia, or the protoxide of strontium 1 \Miat is the combining 
number of strontia ? What is the difference between strontia and baryta'? VThoX is quick- 
lime 7 How may quickhme be decomposed, and calcium, its metalHc base, oe separated? 
What is the appearance of calcium ? How is calcium converted into quicklmie 7 What 
effect is produced when calcium is thrown into water 1 



228 METALS 

CALCIUM AND OXYGEN. 

Oxide of Calcium — 28. 

1 p. Calcium 20+1 p. Oxygen 8. 

Quicklime. 

From the quantity of hydrogen evolved by the action ot 
calcium on water, it has been determined that lime is com 
posed of 

Calcium, 1 equivalent 20 

Oxygen, 1 do. 8 



Making the equivalent for lime, 28 

Carbonate of lime exists in great abundance as a natural 
product, under the names of limestone, marble, and chalk, 
Quicklime, the pure earth, is obtained by exposing the car- 
bonate to heat, and is a substance of great importance in the 
arts, and particularly in building. Mortar is composed of this - 
substance combined with water, and mixed with a proportion 
of sand. 

Quicklime absorbs water with remarkable avidity, and at 
the same time a high degree of heat is produced. This pro- 
cess is called slaking, and the heat is caused by the conden- 
sation of the water into a solid state, in consequence of which 
caloric is evolved. The lime will remain perfectly dry after 
having absorbed one third of its weight of water, which there- 
fore forms a part of the slaked lime, or hydrate of lime. 

Hydrate of lime is composed of 

28 parts or 1 proportion of lime 
9 parts, or 1 do. of water . ,. 

37 is therefore its combining number. 
Lime is very sparingly soluble in water, and it is a singular 
fact, that it is more soluble in cold, than in hot water. Thus, 
Mr. Dalton found that one grain of lim.e, at the temperature 
of 212° required 1270 grains of water for its solution, while 
at the temperature of 60°, the same quantity was dissolved in 



How is the combining proportion of oxygen with calcium determined 1 What is the 
composition of lime, or oxide of calcium 1 What is the equivalent number for lime" 
What causes the heat, when water is thrown on quicklime 1 What is the scientific name 
for slaked quicklime? What is the composition of hydrate of lime 7 Wliai singulai 
fact is mentioned concerning the solubility of lime in cold, and hot water '? 



CHLORIDE OF LIME. 229 

778 grains of water. By other experiments, it has been 
found that water, at the freezing point, will take up just twice 
the quantity of lime that it will at the boiling point. Conse- 
quently, on heating lime water, which has been prepared in 
the cold, a deposition of the lime will ensue. Lime water, 
therefore, when used for medicinal purposes, should be pre- 
pared in cold, instead of hot water, as commonly directed, 
and should also be kept in a cool place. It should likewise 
be closely stopped from the air, for, as the lime has a strong 
attraction for carbonic acid, of which the atmosphere always 
contains a small portion, if left open, it is soon converted into 
carbonate of lime, as shown by the production of a thin pelli- 
cle on its surface. 

Lime water is a delicate test for the presence of carbonic 
acid, with which it forms a white insoluble compound, the 
carbonate of lime. The air from the lungs contains a small 
quantity of carbonic acid, and hence, on blowing into a vessel 
of clear lime water, it instantly becomes cloudy, or turbid. 

LIME AND CHLORINE. 

Chloride of Lime — 92. 

2 p. Lime 56-|-l p. Chlorine 36. 

Oxymuriatt of Lime. Bleaching Powder, 

The gas called chlorine, as already shown, possesses strong 
bleaching or whitening powers ; but as it would be incon- 
venient to manufacture this gas at every place where it is 
wanted, and as its application is more convenient when com- 
bined with some other substance, it is found that in practice, 
these purposes are best answered by first combining it with 
lime. The manufacture of bleaching powder is a business 
of great importance, and is carried on in large establish- 
ments prepared for the purpose. 

The retorts, in vv^hich the gas is extricated, are made of lead 
or platina. If of lead, they must be of new metal and cast, 
for the gas acts on tin, a part of the composition of solder, 



IIow much more lime will water dissolve at the freezing than at the boiling point ? 

Had lime water, for medicinal purposes, ought to be made with hot or cold water % W'hy 7 
\ Why should Tme water be closely stopped from the air 1 Why does lime water become 
: cloudy when air from the lungs is blown into it 7 What is the chemical name for bleach 
1 ing powder 7 Does the bleaching property exist in the lime or in the chlorine 1 What are 

the advantages of combining the chlorine with the lime for this purpose? Why musl 

new lead be used for retorts in making chlorine 7 

20 



230 CHLORIDE OF LIME. 

and since old lead generally contains a portion of this metal, 
owing to its having formerly been soldered, it is soon destroy- 
ed. These retorts are placed in iron vessels of water, to ' 
which the heat is applied. In large manufactories, each re- 
tort is capable of containing 10 cwt. of common salt, ground ' 
'with from 10 to 14 cwt. of black oxide of manganese, in pro- ': 
portion as the latter contains more or less oxygen. This - 
being introduced, there is added from 16 to 18 cwt. of sul- 
phuric acid, of the specific gravity of 1650. The lime, recently 
slaked, is contained in trays, or shallow boxes of wood, placed 
in a large chamber, built of granite, or siliceous sandstone, 
or lined on the inside with lead. This chamber has two 
windows of glass opposite to each other, through which the 
workmen are enabled to see how the process goes on. Every 
part of this chamber is made air tight, the door being secured 
by fat lute, and strips of cloth. 

In order to get rid of the remaining gas, after the absorp- 
tion of the lime is completed, there are three trap doors, one 
in the roof, and two in the floor or sides of the chamber. 
These are opened by means of ropes and pullies, so that the 
workmen may avoid the vapor that passes out. 

The lime being placed in the boxes, the gas is let in to the 
chamber from the retorts, under which a fire is afterwards 
kindled, in order to hasten the process, and obtain more 
chlorine. The gas, being heavier than air, is let in at the 
upper part of the room, and gradually descends, while the 
air in part mixes Avith it, and in part rises above it. 

The lime absorbs the chlorine w^ith great avidity, its con- 
densation causing the evolution of a large quantity of caloric ; 
the latter circumstance is, however, to be avoided, as too high 
a heat partly decomposes the chloride of lime, by expelling 
the oxygen, and thus forming a chloride of calcium instead i 
of a chloride of lime. The gas is, therefore, admitted slowly, 
in order to avoid this consequence. 

The process continues four days, before the absorption is 
considered sufficient to make the best bleaching powder, for 
its quality depends entirely on the quantity of chlorine which 
the lime contains* 



Describe ihe chamber in which the lime, for making tlie chloride of lime, is placed, 
What contains the lime, when placed in the chamber ? Into what part of the room is the 
chlorine admitted 1 Why must the chlorine be admitted slowly 1 If the heat rises too 
high, why is there a muriate instead, of a chloride of lime, formed? How long a time is 
ref,(Uired for making the best bleaching powder 7 



CHL0RID£ OF LIME. 231 

In some manufactories, the lime is stirred by means of 
rakes, with long handles passing through the sides of the 
room, the passages being made close, by means of milk of 
lime, or lime moistened, so as to be about the consistence of 
cream, and contanied in boxes through which the handle 
passes. In others, the traps above described, are opened at 
the end of two days from the beginning of the process, and 
when the gas has subsided, the workmen enter and rake 
over the lime, so as to present a new surface to the action o 
the gas. The doors and traps are then closed, and the gas 
admitted for two days more, at the end of which time the 
process is finished, and the doors are again opened, and the 
chloride of lime removed, and put into close casks for use. 

In general, according to Mr. Gray, a ton and a half of 
good bleaching powder is considered the average product of 
each ton of the salt employed. 

It is said that the principal difficulty in the manufacture of 
this article, is the production of chloride of calcium, by de- 
composition, instead of the chloride of lime. To understand 
the cause of this difficulty, it must be remembered, that cal- 
cium and chlorine have a stronger affinity for each other than 
calcium and oxygen. Lime is composed of calcium and 
oxygen ; and chloride of lime is therefore composed of oxy- 
gen, calcium, and chlorine. Now these three elements being 
present, there is formed a chloride of calcium, in consequence 
of the cause just stated ; and in proportion as this is formed, 
the bleaching property of the salt is destroyed, this property 
being possessed only by the chloride of lime. The same 
effect is produced when the temperature is raised too high 
during the manufacture of this compound, for then the oxy- 
gen of the lime or base is expelled, and the calcium and 
chlorine form chloride of calcium. The only mode of avoid- 
ing this difficulty, appears to consist in admitting the chlorine 
slowly, as already stated. 

This salt is also subject to decomposition from other causes. 
When mixed with water, and exposed to the action of the 



In what manner is the hme stirred, in order to hasten its absorption of the chlorine 7 
What proportion does the bleaching powder formed bear to the quantity of salt employed J 
What is said to be the principal difficulty in the manufacture of bleaching powder 1 
What is the difference in composition between muriate of lime and chloride of lime 1 
Explain the chemical changes which take place when chloride of lime is decomposed by 
oeat, and converted into muriate of lime. 



232 CHLORIDE OF LIME. 

atmosphere, carbonic acid unites with the lime, while the 
chlorine is expelled, and thus a carbonate instead of a chlo- 
ride remains, or by decomposition of the water, a muriate of 
lime is formed, which is also without bleaching properties. 

As the goodness of bleaching powder depends entirely on 
the quantity of chlorine it contains, it is a matter of great 
consequence to the purchaser to ascertain its quality in this 
respect, by actual experiment. According to the experiments 
of Dr. Ure, lime, under a slight pressure, is capable of con- 
densing nearly its own weight of chlorine; but according to 
the same author, the bleaching powder of commerce always 
contains a considerable proportion of the muriate of lime, 
while the chloride itself often does not contain more than one 
half or one third the quantity of chlorine which the lime is 
capable of absorbing. Hence the consumers of this article 
are often cheated out of one half or two thirds of the price 
they pay for it, besides the delay and vexation incident upon 
the failure of the process in which it is used. The manufac- 
turers of paper and cotton goods are often sensible of this fact, 
by experience. 

It appears, on experiment, that when bleaching powder is 
kept for a considerable time, even in properly secured ves- 
sels, such as glass bottles well corked, that it still slowly un- 
dergoes the same change, which is immediately effected by 
heat, as described above. This seems to be in consequence 
of the superior affinity of chlorine for the calcimn, or the 
metallic basis of the lime, by which the oxygen is slowly 
disengaged, and a chloride of calcium, or muriate of lime, is 
formed, and thus the bleaching power is in process of time 
entirely destroyed. 

The principal expense of manufacturing chloride of lime, 
being that of the chlorine itself, and there being no method 
of ascertaining its quantity, except by experiment, the pur- 
chaser generally has to depend chiefly on the honesty of the 
manufacturer, for the goodness of the article, even when re- 



I In what manner is chloride of lime decomposed, when it is exposed to the atmosphere 1 
On what does the bleaching property of the chloride depend? Wliat quantity of chlorine 
is lime capable of absorbing 1 According to Dr. Ure, what does the bleaching powder of 
commerce contain besides the cbJoride of lime 1 What kind cf decomposition doe» 
Weaching powder slowly undergo when confined in close vessels % 



CHLORIDE OF L1M£. 233 

Gently made. But as there are several causes of decompo- 
sition, even when it is honestly and carefully made, the buyer 
is still liable to be deceived, unless he makes his experiment 
before the purchase 

Under such circumstances, the English chemists have de- 
vised several simple methods of testing the quality of bleach- 
ing powder, in order that the buyer might judge of its good- 
ness without actual trial at home. 

One of these methods is, to expose the salt to a sufficient 
degree of heat to expel the oxygen from the lime, and by 
measuring its quantity, to judge of the quantity of the chlo- 
ride of lime. The quantity of oxygen thus expelled, indicates 
the quality of the bleaching powder, so far only as regards 
the quantity of muriate of lime with which it is mixed ; for 
as above stated, the base of the chloride contains oxygen, 
while the muriate contains none. But in addition to the im- 
perfection of this method in not indicating the actual quan- 
tity of chlorine present, there is much difficulty in ascertain- 
ing the quantity of oxygen by it, since various proportions of 
chlorine might also be disengaged by the heat, along with 
the oxygen. This method cannot therefore be readily or 
generally employed. 

It has also been proposed, to analyze the powder by nitrate 
of silver. But this test only indicates the quantity of muriate 
of lime, by forming with the muriatic acid an insoluble chlo- 
ride of silver. This test is therefore useless. 

Several other methods have been tried, and among them, 
that of destroying the color of a certain quantity of indigo 
has been most employed. 

A known quantity of indigo being in solution, a certain 
number of grains of the povv^der is added, and the strength of 
the latter ascertained by the amount of coloring matter de- 
stroyed, or by the number of grains required to discharge, 
entirely, the color of a certain quantity of indigo. 

This method has the advantage of simplicity, but is defec- 
tive in other respects, and particularly so in regard to the 
difference in the quantity of coloring matter in different kinds 
or specimens of indigo. 

The most accurate method is to decompose the chloride 



On what principle has it been proposed to ascertain the goodness of bleaching powder 
by the quantity of oxygen it contains? How is the goodness of bleach' ng powder tested 
tv means of a solution of indigo 1 What is the defect in this method 7 

20* 



234 PHOSPlIURtT OIF LUttt. 

of lime confined in a glass tube, over mercury, by means of 
muriatic acid. The chloride by this means would only be 
decomposed, and converted into the muriate of lime, while 
the muriate already formed, would remain as before. By 
this process the chlorine of the chloride is set free, unmixed, 
and its quantity readily measured by the tube in which the 
experiment is made. 

There being no standard of the quantity of chlorine which 
the best bleaching powder ought to contain, it is by the com- 
parison of different specimens only, that the purchaser can 
be guided. 

Experiments have long since shown, that chlorine has the 
power of combining w^th, or in some other manner, neutral- 
izing, or destroying, the fetid exhalations arising from putri- 
fying substances, and of preventing their deleterious effects. 
In cases of infectious disease, therefore, it is highly useful, 
for this purpose, a table spoonful or two of the pcwder is 
mixed with a pint of Avater, and placed in the sick room, and 
sprinkled in the rooms adjoining. The fetid effluvia from 
putrid w^ater, from sink drains, or from any other source, is 
immediately destroyed by the application of a quantity of the 
chloride. 

By placing a sheet, wet with the chloride of lime water, in 
the bottom of the coffin, and afterwards often sprinkling the 
shroud with the same, the bodies of the dead may be pre- 
served without offence for many days in the hottest season. 

Phosphiiret of Lime. This compound is formed by passing 
the vapor of phosphorus over fragments of quicklime, at a red 
heat. The experim.ent may be performed in the following 
manner. 

Having procured a tube of green glass about a foot and a 
half long, and half an inch in diameter, stop one end with a 
cork, or otherwise, and place in it a drachm of phosphorus^ 
letting it occupy the closed end. Then holding the tube in 
a horizontal position, push into it wdth a wire, or rod, pieces 
of fresh burned quicklime about the size of peas, until they 
fill the middle part of the tube, taking care that the lime does 
not reach the phosphorus by two inches. Then stop the 



What is said to be the most accurate method of ascertaining the quantity of chloride 
*n bleaching powder 1 Is there any standard of the strength of bleaching powder 1 What 
ie said of the disinfecting power of chlorine 1 What is phosphuret of lime 7 Descritw 
ihe process of making the phosphuret of limo. 



MfiTALS. ^5 

mouth of the tube loosely, to prevent the free access of the 
air, but leaving room for that in the tube to pass out as it ex- 
pands. 

Next, heat that part of the tube containing the lime red 
hot, by means of a chafing dish of coals, at the same time 
keeping the phosphorus cool by a wet rag passed round the 
end of the tube. When the lime is seen to be at a red heat, 
bring a hot iron or lamp under the phosphorus, which will 
soon be turned into vapor, and passing over the lime, the two 
substances combine, and form the phosphuret of lime. 

When phosphuret of lime is thrown into water, mutual de- 
composition ensues, and there rises bubbles of phosphuretted 
hydrogen through the fluid, which take fire on reaching the 
air. The phosphorus absorbs the oxygen from the water, 
thus liberating the hydrogen, which combines with a portion 
of phosphorus, forming the gas above named. 

Order 2. — Metals which are supposed to be analogous to 
order 1st, but whose properties are but little known. These 
are, 

Magnesium Ittrium and 

Glucinum Aluminum Zirconium 

Magnesia, glucina, ittria, alumina, and zirconia, before 
the galvanic experiments of Sir H. Davy, have been known 
under the general name of earths, and were considered pure 
elementary substances. When these earths are submitted 
to the action of a powerful galvanic battery, they all give 
more or less evidence that their bases are metals combined 
with oxygen. Magnesia, for instance, when exposed for a 
long time to the action of a powerful battery, in contact with 
mercury, appears to be decomposed ; for the mercury be- 
comes enlarged in bulk, and losing- its fluidity, shows signs 
of having formed an amalgam with the metallic base of the 
magnesia. When this amalgam is heated in a close vessel 
out of contact with the air, the mercury is driven off", and 
there remains a dark gray film, of a metallic appearance, 
which, when exposed to the action of oxygen, is converted 



When phosphuret of lime is thrown into water, what are the chemical changes pro- 
duced 1 What is the definition of order 2d. 7 Whai are the names of the substances 
belonging to order 2d. 7 Under what names were these substances known before the ex- 
periments of Sir H. Davy 1 Were they formerly considered compound, or elementary 
tediefr t What is the reason for supposing that magnesia has a metallic base 1 



236 EARTiiS. 

into a white powder, having the properties of m^'.^n^.sia. It 
is therefore concluded, that magnesia has a metallic base, 
though the metal itself has never been separated in such 
quantities as to allow any further examination of its proper- 
ties than those above stated. 

When the earth alumina, which is the base of alum, is 
brought into contact with the vapor of potassium at a white 
heat, and in a close vessel, the potassium is converted into 
potash. Now, as potassium is converted into potash only by 
the absorption of oxygen, and as the oxygen could have been 
derived from no other source except the alumina, such an ex- 
periment shows that alumina contains oxygen, and therefore 
by analogy, there is reason to suppose that alumina is com- 
posed of the metal aluminum and oxygen. 

The other earths above named, when submitted to similar 
experiments, have each shown that they contained oxygen ; 
and as potash, soda, and lime, are known to be metallic ox- 
ides, that is, to consist of a metal combined with oxygen, it is 
inferred that the earths, possessing similar properties, are 
also composed of a metal united with oxygen. It is therefore 
agreed among writers on chemistry, that the bases of these 
earths should be arranged as metals, under the names above 
specified; though their existence, with perhaps the exception 
of magnesium, has never been directly proved. 

In consequence of the discovery, or the inference, that the- 
earths possess metallic bases, their names, in conformity with 
the language of chemistry, are changed from words denoting 
simple bodies, to such as denote compounds. Thus, the earth 
formerly called magnesia, is now known under the nam.e ol 
oxide of magnesium, and the simple term alumina, is changed 
to oxide of aluminum, the same language being adopted with 
respect to all the other earths above named. 

Properties of the Earths. 

Magnesia, or oxide Magnesium. Pure magnesia is well 
known as a medicine, under the name of calcined magnesid. 
This is obtained by exposing the carbonate of magnesia to a 
red heat It is white, tasteless, and inodorous, but possesst:^s 



What te the reason for supposing that alnmina has a metallic base ? On what grounds 
(8 li believe^ that the other earths belonging to this order have metallic bases 1 What are 
ttte scientific ames of magnesia and alumina, supposing them to be the oxides of metal3l 
How ie pure m ^nesia obtained "S What effect does magnesia have on vegetable colors 1 



i 



METALS. 237 

flight alkaline properties, being capable of changing the blue 
colors of vegetables to green, and of neutralizing the acids, 
with which it forms various saline compounds. One of these, 
the sulphate of magnesia, or Epsom salt, is a well known 
medicine. 

Magnesia, in a few instances, has been found in the native 
state, but always in small quantities only. That sold by 
apothecaries is obtained from certain springs, as that of Ep- 
som, where it exists, in combination with sulphuric acid, 
forming Epsom salt, which is dissolved in the water. 

Calcined or pure magnesia, if exposed to the air, absorbs 
carbonic acid, and is converted into a carbonate. Hence, a 
large proportion of that used in medicine, and sold for cal- 
cined, is in truth the carbonate, the change being effected by 
carelessness, in exposing the calcined to the air. 

Alumina, or Oxide of Aluminum. The earth alumina is one 
of the most abundant productions of nature, every description 
of clay being an aluminous earth, of a greater or less de- 
gree of 'purity. The clay, of which bricks, pipes, and earthen 
ware are made, consists chiefly of this earth. The ruby and 
the sapphire, two of the hardest and most beautiful of gems, 
are also composed of alumina. Pure alumina, for experi- 
ment, is most easily obtained from alum, which is a sulphate 
of alumina and potassa. To obtain the earth, dissolve one 
part of alum in six parts of boiling water, and when the so- 
lution is cold, add one part of carbonate of potash. By this 
process the sulphate of alumina is decomposed, in conse- 
quence of the strong affinity existing between the potash and 
sulphuric acid, and two new^ salts are formed, viz. sulphate of 
potash and carbonate of alumina, the latter being precipitated 
to the bottom of the vessel. This precipitate being washed, 
and then exposed to a red heat, to expel the carbonic acid, is 
pure alumina. 

The substance, thus procured, is white, inodorous, soft to 
the touch, and tasteless. Mixed with water, it forms a mass 



What is the most commoa salt of which magnesia is the b£^e 1 How is pure mag. 
' nes:a converted into a carbonate 7 How is the uncertainty of magnesia, as a medicine, 

accounted for 7 What is the earth of which clay is chiefly composed 7 What common 
1 articles and what precious stones are composed of alumina '? How may pure alumina 

be obtained 1 What chemical changes take jjlace when alum, in solution, is mixed ^ith 

carbonate of potash ? What is the appearance of pure alumina 7 



238 METALS. 

which IS exceedingly plastic, and may be worked into all 
shapes. The tenacity of every kind of clay is owing to the 
alumina it contains. 

Alumina, being insoluble in water does not affect the co- 
lors of vegetables. It, however, performs the part of an 
alkali in neutralizing the acids, and forming with them saline 
compounds. 

Glucina, or Oxide of Glucinum. The earth called glucina 
has been discovered but in small quantities, being known to 
exist only in the minerals, emerald, beryl, and euclase. Its 
name comes from a Greek word signifying sweet, because 
some of its combinations are sweet to the taste. In some of 
its properties it resembles alumina, and in others it differs 
from all the other earths. One of its distinctive properties 
is that above mentioned, of forming a compound, when dis- 
solved in sulphuric acid, which is sweet to the taste. 

Iltria, or Oxide of Ittrium. Ittria resembles alumina and 
glucina in most of its chemical properties, but differs from 
them both, in being insoluble in a solution of pure potash. 
This earth has been found only in a single rare mineral, in 
Sweden. It forms peculiar salts, when combined with the 
acids, and is thus known to differ from all the other earths. 

Zirconia, or Oxide of Zirconium. This earth is also ex- 
ceedingly rare, having been detected only in the zircon, a pre- 
cious stone found in Ceylon, and the hyacinth of France. 
It resembles alumina and the other earths in being a white 
soft powder. Its salts are distinguished by being precipitated 
from their solutions by all the pure alkalies. 

Zirconium, the base of this earth, was separated from its 
oxygen, by the Swedish chemist, Berzelius, in 1824. It Ava.^ 
in the form of a black powder, which took fire in the opei 
air at a temperature far below a red heat, and burned with ; 
bright flame. The product of the combustion was zirconia 
But whether this base is of a metallic nature, has not been 
decided. It is wanting in one property common to all metals, 
being a non-conductor of electricity. 

Silica, or Oxide of Silicium. Sir H. Davy's experiments 



In what minerals does the oxide of glucina exist 1 What is the meaning of the word 
glucina, and why is this earth so named % How does ittria differ from alumina and glu- 
cina ? In what minerals has the earth zirconia been found 1 How are the salts of sirco- 
nia distinguished 1 What is said of the metallic base of zirconia 1 Wliat is said of tlw 
metallic base of silica I 



METALS. 239 

on silica lead him to suppose, that in common with the earths 
above described, it had a metallic base, and it was arranged 
with them, in conformity to this opinion. But more recently, 
Berzelius has succeeded in decomposing this earth, and has 
given an account of the properties of its base. From this we 
learn that silicium is of a dark brown color without the least 
trace of metallic lustre. That it is incombustible in the open 
air or in oxygen gas, and that it may even be exposed to the 
flame of the* blowpipe without fusion, and without suffering 
the least change. It is not dissolved by any of the acids, ex- 
cept a mixture of the nitric and fluoric, with which it readily 
enters into solution. It is not a conductor of electricity. 
These properties, and particularly its w^ant of metallic lustre, 
and of power to conduct electricity, prove that the base of 
silica is not of a metallic nature. 

Silica, orsilex, is a very abundant natural product. It forms 
a large part of all granitic, or primitive rocks, and moun- 
tains, and is the chief ingredient in sandstones, and earthy 
formations. Rock crystal, or quartz, flint, chalcedony, agate, 
cornelian, and all other substances of this kind, are composed 
almost entirely of silex. 

Silica maybe obtained in sufficient purity, for most purpo- 
ses by heating transparent rock crystal to redness and plung- 
ing it into water while hot, and then reducing it to powder. 

In this state, silex is a white powder, which feels harsh 
when rubbed between the fingers, and has neither tastenor 
smell. It is exceedingly infusible, but may be melted wnth 
the compound blowpipe. It resists the action of all the acids, 
except the fluoric, which dissolves it w^th considerable faci- 
lity. It is dissolved by the fixed alkalies, and hence it would 
appear that its properties are rather of an acid, than of an al- 
kaline nature. On this account several chemists have called 
silica an acid, and the compounds w^hich it forms with the 
alkalies, have been termed silicates. 

From what has been said, the student wdll infer that there 
is yet considerable doubt and uncertainty, in respect to the 
real nature of silica. 

Dr. Thompson, being convinced of its non-metallic nature, 



Is the base of silica of a metallic nature 7 W^at substances are mentioned of which 
silica forms the principal part? How may pure silica be obtained? WTiat are the pro- 
r»enies of silica 7 What is said of the compound nature of silica? 



240 METALS. 

arranges it with the simple bodies carbon and boron. There 
is no doubt, however, from the experiments of Davy and Ber- 
zelius, of its compound nature ; and that it consists of a base 
combined with oxygen, has been proved by direct experiment. 
But that its base is not a metal is proved from its want of lus- 
tre, and power to conduct the electric fluid, these two proper- 
ties being essential to all metallic bodies. 

Silex in the form of sand, is a principal article in the ma- 
nufacture of glass. The common dark colored, or green 
glass, is composed of impure sand, which contains oxide of 
iron, melted Avith kelp, wood ashes, or impure potashes. 
Crown glass, for windows, is composed of white sand, fused 
with a purer alkali. Plate glass, for looking glasses, is made 
of still purer materials ; and what is known by the name of 
flint glass, of which decanters, and other ornamental or cut 
glassware is made, is composed of the purest sand and al- 
kali, Avith the addition of a considerable portion of lead, which 
is added in the form of litharge, or red lead. This is the 
softest and hea^dest kind of glass. It cuts more easily, and 
withstands the changes of temperature much better than glass 
containing no lead. 

Order 3. — Metals which decompose water at a red heat, 
These are, 

Manganese, Iron, and 

Zinc, Tin, Cadmium. 

The power of a metal to decompose Avater, depends on its 
affinity for oxygen. In some instances, as in those of potas- 
sium and sodium, already given, the metals hai^e so strong 
an affinity for oxygen, as to absorb it from AA^ater, at common 
temperatures. Other metals do not decompose this fluid at 
any temperature, such being the 4th order of the present class. 
Those noAv to be examined, have an affinity for oxygen, Avhich 
they sloAAdy absorb from the atmosphere, and a part of Avhich 
they retain at high degrees of heat. But their attraction for 
oxygen is not in sufficient force to decompose AA^ater, except 
Avhen heated to redness, Avhen the combination is effected 
Avith considerable rapidity. 



AVhat use is made of silex in the arts 1 Explain the difference between green glass, 
crown glass, and plate glass. AVhat is the composition of cut glass ? What is the defi- 
nition of order 3d 7 What metals bel'»vg to order 3d 7 On what property of a metal does 
Its power to decompose water depend 7 



METALS. 24. 

MANGANESE 28. 

This metal always occurs in nature in combination with 
oxygen, and which it holds with such force as to require the 
most intense heat for its removal. The metal may, however, 
be obtained in a pure state, by exposing the black, or per- 
oxide, mixed with a com.bustible, to the highest heat of a 
smith's forge. The combustible, which may be pitch or 
powdered charcoal, with Avhich the oxide is mixed, is thus 
made to absorb the oxygen, and the metal is found at the 
bottom of the crucible. 

Manganese is of a dusky white color, with a specific gra- 
vity of 8. When exposed to the air it absorbs oxygen, and 
soon falls into powder, which afterwards changes its color 
from gray to brown, and from brown to black, according to 
its grade of oxidation. When this metal is exposed to a red 
heat, and the steam of water is passed over it, decomposition 
takes place, the oxygen of the water combines w4th the man 
ganese, and the hydrogen is disengaged. 

MANGANESE AND OXYGEN. 

Peroxide of Manganese — 44. 

1 p. Manganese 28+2 p. Oxygen 16. 

Black Oxide of Manganese. 

This compound occurs abundantly in nature, and is known 
under the name of hlack oxide of manganese. It is found in 
imorphous masses, of a dark gray or nearly black color, and 
is commonly mixed with various proportions of sand, oxide 
of iron, carbonate of lime, or other impurities. In its pure 
state, it occurs in the form of prismatic crystals of a dark 
color, and slightly metallic lustre. 

In this state the metal contains its full proportion of oxygen, 
and undergoes no change on exposure to the air, or to a 
moderate heat. When heated to redness, it parts with one 
proportion of oxygen, and is converted into a deutoxide. In 
this manner oxygen gas may be obtained. The peroxide of 
manganese is of considerable consequence in the arts, and 



In what state does manganese occur in nature T By what process niay metallic man- 
ganese be obtained from the oxide 1 What is the appearance and specific gravity of 
manganese 7 Under what circumstances does manganese decompose water 7 What 13 
the scientific name for black oxide of manganese? When peroxide of manganese is 
heated to redness, what chemical change does it undergo"? Of what u?^ is peroxide of 
mansaneso in the arts 1 

21 



242 METALS. 

particularly in the formation of chlorine for the manufacture 
of bleaching powders, and also in furnishing oxygen gas for 
other chemical uses. The methods for obtaining these gases 
have already been described. 



The peroxide of mercury is composed of 

1 proportion of manganese, 28 

2 proportions of oxygen, 16 



44 

There are two other oxides of manganese, viz. the frotox 
ide, and the deutoxide. There is also reason to believe that 
manganese is capable of combining with such proportions of 
oxygen as to form acids ; but the subject has not been sulfi- 
ciently investigated to determine the composition or nature 
o[ these compounds. 

Manganese combines with the acids, and forms a variety 
of salts, which are either colorless, or of a reddish or pink 
hue. These salts are found only in the laboratory of the 
chemist, and are of no use in the arts. At a red heat this 
metal decomposes water. 

IRON — 28. 

This well known metal has a gray color, and a strong 
metallic lustre, which is much improved by burnishing. Iron 
is at once the most useful, the most abundant, and the most 
universally diffused of all the metals. It is found in the 
mineral, the vegetable, and the animal kingdoms, and in 
some countries it exists in such quantities as to form moun- 
tains of considerable size. 

Yv^hen heated, it becomes soft and malleable, and in this 
state two pieces may be incorporated, or welded together, by 
hammering. Its specific gravity is about 8. It is attracted 
by the magnet, and may itself be made permanently magnetic. 
This property is of vast consequence to the world, being pos- 
sessed by no other metals except nickel, and cobalt, and by 
these in a much inferior degree. 

Iron has a strong affinity for oxygen, and when exposed tc 
air and moisture, soon rusts or oxidates on its surface. In a 
perfectly dry atmosphere, how^ever, it undergoes little or no 
change, a proof that it absorbs oxygen with more facility 

What is the composition of the peroxide of manganese 1 What is said of the acids of 
manganese 7 What is the combining number for iron 7 What is said of the abundance 
and usefulness of iron 7 What is said of the affinity of iron for oxygen ^ 



M£TALS. 243 

from water than from the air. When heated, it attracts oxy- 
gen both from air and water, with great rapidity. When 
the steam of water is passed over iron, at a red heat, the wa- 
ter is decomposed, its oxygen combining with the metal, 
while the hydrogen is set at liberty. When heated to red- 
nes-s, in oxygen gas, it burns with intense brilliancy. Iron is 
exceedingly ductile, and maybe drawn into wire not exceed- 
ing the thousandth part of an inch in diameter ; but it cannot, 
like gold and silver, be hammered into thin leaves, and there- 
fore is not highly malleable. 

The ores of this metal are very numerous, and some of 
them highly beautiful and interesting. They are chiefly sul- 
pliurets and oxides, but the oxides are the only ores from 
w liich the metal is obtained. 

Iron has, in a few instances, been found in its native state, 
mixed with lead and copper, or w^ith some earthy substance. 
It has also been found in large masses, alloyed with five or 
six other metals, and called meteoric iron, from an opinion that 
these masses fell from the clouds. Native iron is soft and 
malleable as it occurs, and does not difl!er from that which 
has been reduced from its ores and purified. 

Cast iron contains variable proportions of carbon and oxy- 
gen, *and in this state it is hard and brittle. These impuri- 
ties are detached by the process of refining, and then the iron 
becomes soft and malleable. 

Steel is made by heating pure iron with carbon, or char- 
coal, by which it is rendered exceedingly hard and brittle. 
This change is produced in consequence of the absorption of 
a portion of carbon by the iron. Steel, therefore, is compo- 
sed of iron and carbon, and its scientific name is carburet of 
i ^'on, 

IRON AND OXYGEN. 

Oxide of Iron, 
Rust of Iron. 

iron combines with oxygen in two proportions, forming the 
Dlue and red oxides of this metal. 



Under what circumstances does iron decompose water % In what does this decomposi- 
tion consist? What is said of the ductility and malleability of iron 1 In what state does 
iron occur aa a natural product? What is the ore from which iron is extracted 1 Wha^ 
id meteoric iron ? What are the impurities contained in cast iron ? How is steel made > 
WTiat is the composition of steel 1 What is the scientific name of steel 1 



244 METALS. 

Protoxide of Iron. The black or protoxide of this metn 
is formed by passing dry hydrogen over the red oxide, at a 
temperature a little below redness. This oxide is composed 
of 1 equivalent of iron 28, and 1 equivalent of oxygen 8. Its 
combining number, therefore, is 36. 

The Black Oxide of Iron, which occurs in the form of 
scales, when iron is heated and hammered in the open air, is 
not a definite compound, but a mixture of the black oxide and 
metallic iron. 

Peroxide of Iron. This is the red oxide, and is known to 
mineralogists as a native compound, under the name of red 
hematite. The same article is known to button makers, and 
other artists, under the name of blood stone, and is employed 
to polish their work. The peroxide may be prepared by art, 
by dissolving iron in nitric acid, then precipitating it with 
ammonia, and heating the precipitate to a little below red- 
ness, to drive off the acid. Its color and other properties are 
like those of the native red oxide. The peroxide of iron is 
composed of iron 28, and oxygen 12. 

The Brown Oxide of Iron is composed of precisely the 
same proportions of the metal and oxygen as the red oxide, 
but in addition to these ingredients, it contains one proportion, 
or 9 parts of water. 

The other oxides of iron are either mixtures of the red and 
blue oxides, or one or both of these oxides containing vari- 
ous impurities. The great number of oxides of this inetaL 
described in books of mineralogy, and differing from each 
other in color, hardness, and form, arise from such mixtures 
Thus, the magnetic oxide of iron, or native magnet, is com- 
posed of peroxide of iron 71, and protoxide 29 to the 100. 
The brown oxides of iron all contain water, and are, therefore, 
called hydrates. The ochres are of this kind. 

Iron combines with carbon, sulphur, iodine, phosphorus, 
and the different acids. Its compounds are, therefore, ex- 
ceedingly various, in respect to form, color, and properties. 
We shall, however, examine only two or three of these com- 
pounds here, the salts being reserved for another place. 

Carhwret of Iron. Steel, we have already said, is a car- 
ouret of iron. This important metal is manufactured from 



In how many proportions does oxygen combine with iron 1 What are the names of 
these oxides'? What is the composition of the protoxide 7 What is the composition ol 
tiie peroxide of iron ? How does the brown differ from the red oxide of iron 7 What is 
the composition of the native magnet 7 What substances are mentioned with which irou 
combines* 



MKTALS. 245 

the iron, by exposing the latter to a long continued red heat, 
in contact with charcoal. For this purpose, the purest mallea- 
ble iron, in bars, is employed, and is found to gain in weight, 
one pound in 150, by the process. Steel, therefore, consists 
of iron combined with a 150th part of its weight of car- 
bon, which it absorbs from the fire. When iron is per- 
fectly enclosed, and heated with a fragment of diamond, it is 
converted into steel, in the same manner as when heated 
with charcoal. This experiment shows the identity of car- 
bon and diarnonc, the only difference being the color and 
crystalline form of the latter. It also proves that the hard- 
ness of steel is owdng to the particles of diamond which it 
contains. 

The native carburet of iron, commonly known under tne 
name of black lead, or plumbago, contains 95 parts of car- 
bon and 5 of iron. This substance is infusible at the high- 
est heat of a furnace, and hence is employed in making cru- 
cibles and melting pots. It is also used in making black lead 
pencils. 

Sulphur et of Iron. This compound occurs as a natural 
product, and is known to mineralogists and others, under the 
name of iron pyrites. It is a yellow brittle substance, often 
crystallized in the form of cubes, or octohedrons, with their 
surfaces highly polished. These specimens are generally 
taken for gold, by those who are ignorant of such matters, 
and the places where they are found, are sometimes kept a 
profound secret for years, for fear the owner of the soil should 
claim a part of the wealth. Every mineralogist, on pro- 
nouncing such specimens of no value, has occasionally wit- 
nessed the fallen countenance of the applicant, whose hopes 
and expectations he had thus blasted. Sulphuret of iron may 
also be formed by touching a bar of iron, at a glowing red 
heat, with a roll of brimstone. The compound v^^ill fall down 
in drops. The natural and artificial sulphurets are composed 
of precisely the same definite proportions, viz. iron 28, and 
sulphur 16. 



In what proportion is the weight of iron increased by being converted into steell What 
Is said of converting iron into steel by means of the diamond? What does ihis experi- 
ment prove? What is the composition and the proper name of black lead 1 What are 
the uses of black lead 1 Is sulphuret of iron a natural, or artificial compound 1 What 
is the appearance of the native sulphuret of iron"? What precious metal is this com- 
pound sometimes taken for ? How may sulphuret of iron be formed artificially % Wlial 
ifl Uic composition of sulphuret of iron 1 

21* 



246 M£tALS. 

ZINC — 34. 

Zinc, when pure, is of a bluish white color, and of a stn 
ated fracture, presenting the result of a confused crystalliza- 
tion. When rubbed with the fingers it imparts to them a pe- 
culiar metallic taste and smell. When cold, this metal is not 
malleable, but when heated to between 200" and 300'^, it be- 
comes both malleable and ductile. If its temperature be raised 
to 400", it becomes so brittle as to be readily reduced to pow- 
der, in a mortar. 

Zinc meks at 680 degrees, and if this temperature be in- 
creased, it burns with a bluish flame in the open air. When 
melted with copper it forms the alloy, well known under the 
name of brass. 

This metal never occurs in the native, or pure state, but is 
always found Combined either with sulphur, carbonic acid, or 
oxygen. The sulphuret of this metal, called zinc ble?ide, Sind 
the carbonate, called calamine, are the ores from which zinc 
is obtained. The sulphuret being roasted, that is, submitted 
to a low red heat in the open air, to drive ofT the sul- 
phur, and oxidize the metal, is then melted with charcoal, by 
which the oxygen is absorbed, and the metal reduced. The 
calamine is first roasted to drive off the carbonic acid, and is 
then distilled in iron retorts, by which means the pure metal 
is obtaiified. Tnis latter process is said to have been learned 
of the Chinese, and that a man was sent from Europe to 
China on purpose to obtain the secret. Pure zinc, when ex- 
posed to a white heat in a close vessel, wall, in the same man- 
ner sublime, and again condense, unchanged. 

ZINC AND OXYGEN. 

Oxide of Zinc — 42. 
1 p. Zinc 34+1 p. Oxygen 8. 

Flowers of Zinc. 

When zinc is exposed to a red heat in the open air, it burns 
with a Avhite flame, and at the same time an oxide of the 
metal is formed, which rising by the heatj falls around the 



What is the color of pure zinc ? Under what circumstance is zinc malleable 1 In wha« 
temperature does zinc melt % What is the composition of brass 1 Is zinc ever found in 
the native state 1 What are the names of the ores of zinc, and of what are they com* 
ix)sed 1 How is zinc reduced from its sulphuret 1 How is calamine reduced 7 How is the 
oxide of zinc formed \ 



CADMIUM. 247 

place of combustion in the form of white flakes. This sub- 
stance was formerly called flowtis of zinc, and sometimes 
philosophical wool. It is an oxide of the metal, and the only- 
one known. When this oxide is collected, and again sub- 
mitted to the fire, it does not rise^ as before, but melts into a 
clear glass. 

When the vapor of water is brought into contact with 
metallic zinc at a red heat, the M^ater is decomposed, the zinc 
combining with its oxygen, and forming an oxide, in the same 
manner as is done in the open air. Both these oxides are 
composed by weight, of 

1 atom, or equivalent of ziiic, 34 
1 do. do. oxygen, 8 



Combining number for oxide of zinc, 42 
CADMIUM — 56 

Cadmium is one of the new metals, havmg been disco verea 
in certain ores of zinc, in 1817. This metal in color and 
lustre resembles tin, but is harder and moi'e tenacious. It is 
both ductile and malleable to a Considerable degree. Its spe- 
cific gravity is nearly 8.5. It fuses at a temperature some- 
what less than 500 degrees, and at a little higher heat it rises 
in vapor, and condenses in globules like mercury. 

When cadmium is heated in the open air, like many other 
metals, it absorbs oxygen, and is converted into an oxida 
It is readily dissolved by the nitric acid. When heated in 
contact with the vapor of water, the fluid is decomposed, and 
an oxide of the metal is formed. 

Cadmium combines, so far as is known, with only one pro- 
portion of oxygen. This oxide is composed of 
Cadmium, 1 equivalent 56 
Oxygen, I do. 8 



64 
Cadmium, like the other metals, forms salts by combina- 
.ion with the acids. But these compounds are little known, 
and of no value. 



What was this oxide formerly called 1 How may zinc be made to decompose water % 
What is tiie composition of oxide of zinc, and what is its combining number? What is 
cadmium 1 What other metals does cadmium resemble 1 Is this a brittle or a malleable 
metal 1 What is the specific gravity of cadmium 1 What is the composition of oxide of 
cadmium? 



248 tis. 

TIN— 59. 

Tin must be examined in the state of grain, or block tin ; 
what is commonly called tin, being sheets of iron, merely 
covered with this metal. 

Tin is procured from its native oxides, by heat and charcoal, 
on the same principle that has already been described for iron 
and several other metals. The ores of tin are only two, viz. 
an oxide, and a sulphuret. This metal is not readily oxidized 
by exposure to the atmosphere, though the brilliancy of its 
surface is soon tarnished. It is highly malleable, but not 
equally ductile, its tenacity not being sufficient to allow its 
being drawn into fine wire. Its specific gravity is 8. When 
heated to whiteness, it takes fire in the open air, and burns 
with a white flame, being at the same time converted into an 
oxide ; at a red heat it decomposes water. 

Tin is a highly useful metal, being employed for many va- 
luable purposes in the arts and conveniences of life. Thin 
sheets of iron, being dipped into melted tin, receive a coat of 
the metal, and are thus prevented from rusting. This is called 
sheet tin, and is the article of which the common tin ware is 
made. Tin foil, that is, tin rolled into thin sheets, is used 
for many purposes. Electrical jars are coated with it, and 
the backs of looking-glasses are formed of an amalgam ol 
tin foil and mercury. Block tin forms a part of Britannia 
ware, of princes' metal, of pewter, speculum metal, &c. 

TIN AND OXYGEN. 

Tin combines with oxygen in two proportions : The first, 
or the protoxide, is formed when the metal is kept for some 
time in fusion in the open air. At this temperature it absorbs 
oxygen from the atmosphere, and is converted into a gray 
powder. This powder is the protoxide, and is composed of 

1 equivalent, or atom of tin 59 
1 do. do. oxygen 8 



1 



67 
This oxide is soluble in acids and in ammonia. The so- 

Of what metal is the sheet tin chiefly composed ? How is tin procured from its oxide! 
What are the only ores of tin 1 Is tin readily oxidized by exposure to the air or not4 
What is said of the malleability and ductility of tin 1 What is the specific gravity of tin I 
Into what is this metal converted when burned in the open air 7 How is sheet tin madet 
What are the principal use.^, of tin? In how many profortions does tin combine with 
oxygen 1 How is the protoj^ide of tin formed t 



ARSENIC 249 

cond, er peroxide of tin, is prepared by dissolving the metal 
in nitric acid, slightly diluted with water. It is a powder of 
a yellow color, and is composed of 

1 equivalent of tin, 59 

2 do. of oxygen, 16 

75 

This oxide, when melted with glass, forms white enamel. 

Tin combines with sulphur, chlorine, and the acids, form- 
ing a variety of compounds, some of which are occasionally 
used in the arts. 

Order 4. — Metals which do not decompose water at any 
temperature. These are, 

Arsenic Uranium Titanium 

Molybdenum Columbium Bismuth 

Chromium Nickel Copper 

Tungsten Cobalt Tellurium 

Antimony Cerium Lead 

The last order includes all such metals as attract oxygen 
vvith sufficient force, when heated to redness, to decompose 
water. The present division absorb and retain oxygen at 
high temperatures, but none of them attract that principle, 
even at the highest temperatures, with sufficient force to de- 
compose water. 

ARSENIC 38, 

There are no mines Avorked merely for the purpose of ob- 
taining arsenic, the arsenious acid, the only form in which it 
IS used, being procured by the process of roasting the ores 
of cobalt. The ores of the latter metal, being heated in 
tiirnaces w^ith long chimneys, the acid rises and attaches itself . 
to the sides of the chimney, in layers, or cakes. After a 
considerable quantity has been accumulated in this manner, 
it is scraped off, and purified by a second sublimation, when 



WTiat is the composition of the protoxide of i'ml How is the peroxide of this metal 
l^repared 1 W^hat is the quantity of oxygen contained in the peroxide of tin 1 What is 
the definition of order 4th ? \\Tiat are the names of the metals arranged under the 4th 
order ? Are any mines worked merely to obtain arsenic 1 How is the oxide of ftrsanie 
procured ? 



«50 ARSENIC aND oxygen. 

it forms the well known poison, called white arsenic^ or oxide 
of arsenic. 

From the white oxide the metallic arsenic is procured, by 
heating this with a combustible. 

In legal investigations, where there is a suspicion of poi- 
soning with arsenic, it sometimes happens that justice will de- 
pend on the decision of the chemist, whether arsenic might 
not have been the cause of death. In such cases, very mi- 
nute portions of arsenic may be detected by means of a com- 
bustible and a glass tube, in the following manner : Let the 
matter suspected to contain the poison, be well dried at a 
low heat ; then mix it with five or six times its weight o\ 
powdered charcoal, and put the mixture into a thin glass 
tube, closed at one end. If now heat be gradually applied 
to the tube until it becomes red, the metal, if arsenic be pre- 
sent, will rise and coat its inside, showing a brilliant metallic 
lustre, similar to that of steel. If it is found that, on heating 
a small piece of this metal, it rises in white vapor and gives 
the smell of garlic, it is arsenic beyond doubt. 

The structure of metallic arsenic is crystalline, and its spe- 
cific gravity about 8. When heated to about 360° it sublimes, 
without fusion, its melting point being far above that at which 
it becomes volatile. If the metal is heated in the open air, 
it is converted into the arsenious acid, and again becomes 
poisonous as before ; but, while in the metallic form, arsenic 
has no action on the system, and, therefore, is not a poison. 

ARSENIC AND OXYGEN. 

Arsenious Acid — 54. 
1 p. Arsenic 38-|-2 p. Oxygen 16. 
White Arsenic, Oxide of Arsenic. 

We have stated above, that when metallic arsenic is heated 
in the open air, it is converted into a white substance, 
called oxide of arsenic. This is the arsenious acid of che- 
mists. It differs from the oxides of metals in possessing acid 
properties. It is slightly soluble in water, reddens vegeta- 
ble blue colors, and combines with alkalies, forming salts 



How may arsenic be reduced from its oxide to the metallic state? What is the a^ 
pearance of pure arsenic % What is the specific gravity of arsenic ) Is metallic areer 
e poison! How is arsenious acid formed 1 



METALS. 251 

called ais&ftiits. The arsenite of potash, usually called 
Fowle,' s ^olutiun of arsenic, has been long employed inmedi- 
oine ab a remedy for eruptive, and other diseases. 

ARSENIC AND SULPHUR. 

Sulphur ets of Arsenic. 

Sulphur combines with arsenic in two proportions, form- 
ing compounds which are known by the names of orpiment, 
and realger. These compounds are both of them natural 
products, and may also be formed by art. Realger is of a 
red, or scarlet color, with a shining semi-metallic lustre, 
and is composed of 38 parts of metallic arsenic, and 16 parts, 
or one proportion, of sulphur. 

Orpiment has a rich yellow color, and a foliated structure. 
Its lustre is shining, and somewhat metallic, and it is readily 
separated into layers, like mica. This is composed of 38 
parts, or one atom of metallic arsenic, and 24 parts, or one 
atom and a half of sulphur. 

Orpiment is employed as a paint under the name of King^s 
Yellow. 

CHROMIUM 28. 

The metal, chromium, has been detected only in the two 
'lAative compounds, chromate of lead, and chromate of iron. 
In these two salts, the metal chrome exists in combination 
with so much oxygen as to constitute an acid, which is united 
to the oxides of lead and iron, forming the compounds above 
named. Arsenic, as shown above, forms an acid with oxy- 
gen in the same manner, and we shall see presently that 
several other metals when combined with oxygen perform 
the office of acids. 

Chromium has been procured only in very small quanti- 
ties, by exposing its acid mixed with charcoal, to the highest 
temperature of a smith's forge. It is a brittle metal, of a 



What is the common name of this acid ? What is the form of arsenious acid ? What are 
the salts called which arsenious acid forms with the salifiable bases 1 What use is made 
of arsenite of potash 1 In how many proportions does sulphur combine with arsenic ? 
What is realger 7 What is its composition ? How does orpiment differ from realger T 
What use is made of orpiment? What is chromium 7 In what native compound is 
chromium found 1 In what state does chromium exist in these compounds 1 How has 
«hromiura been procured* 



252 CHROMIUM. 

grayish white color, and very infusible. Its specific gravity 
is 6. 

Chromium combines with oxygen in three proportions, 
forming the following compounc^s: 

Chrome. Oxygen. 

Protoxide, composed of 28 and 8 
Deutoxide, do. 28 do. 16 

Chromic acid, do. 28 do. 24 

The oxides of chrome are of no importance in the arts, 
but the chromic acid forms colored salts with the oxides oif 
the metals which are extensively employed in painting and 
coloring. 

The chromic acid may be obtained in a separate state, by 
boiling the native chromate of lead in powder, with twice 
its weight of carbonate of potash, and afterwards saturating 
the alkali with dilute sulphuric acid. The sulphate of pot- 
ash thus formed, will subside, leaving the chromic acid in 
solution, which on evaporation, will yield crystals of chromic 
acid. 

These crystals are of a ruby red color, and when dissolved 
in water, possess all the properties of an acid. 

The useful compounds formed by combining chromic acid 
with salifiable bases, are prepared from chromate of potash 
in solution. The latter salt is made by heating to redness 
the native chromate of iron with an equal weight of nitrate 
of potash. By this process, the chromate which was in the 
state of an oxide, is converted into chromic acid, by the 
oxygen of the nitre, the acid at the same time combining with 
the potash of the nitre. The ignited mass is then dissolved 
in water, neutralized by nitric acid, and the solution concen- 
trated by evaporation, when the chromate of potash shoots 
into crystals, of a yellow color. 

The chromate of lead, a beautiful paint, at present largely 
employed under the name of chrome yellow, is made by mix- 
ing acetate, or sugar of lead, dissolved in a large quantity 
of water, with solution of chromate of potash. A double 
decomposition of these two salts is thus effected, and acetate 



What is the color and what the properties of chromium 1 1n how many proportions doea 
chromium combine with oxygen 7 What are the names of these compounds 7 Of what 
use is the chromic acid? How may pure chromic acid be obtained? What is the color 
and ftirm of this acid 7 How is chromate of potash prepared 7 How is the chromate oi 
tead ma^e fioaa the chioifnate of potash 7 What is the color and u?e of chromate of lead 1 



METALS. 26S 

of potash and chromate of lead are formed. The acetate re- 
mains m solution, while the chromate being insoluble in 
water, falls down in form of an orange colored, or yellow 
powder. This powder being separated from the liquid, and 
dried, forms the beautiful pigment in question. 

MOLYBDENUM 48. 

The native sulphuret of molybdenum is a ponderous mine 
ral, which occurs in masses, or is disseminated in other 
mirerals. Its structure is foliated, and its lustre like that of 
lead recently cut. When this compound is reduced to fine 
powder, and digested in nitro-muriatic acid, the sulphur and 
metal are both acidified by the oxygen imparted to them by 
the nitro-muriatic acid. On heating the solution, the sulphu- 
ric acid thus formed is expelled, while the molybdic acid re- 
mains in the form of a heavy white powder. From this 
powder the metallic molybdenum may be obtained by expos- 
ing it, mixed with charcoal, to the strongest heat of a smith's 
forge. 

This metal has never been obtained, except in very small 
quantities, and in the form of brilliant w^hite globules con- 
tained in a blackish mass. When heated in the open air, it 
is soon converted into molyhdic acid. 

Molybdic acid is in the form of a white powder, Avhich has 
a sharp metallic taste, reddens vegetable blues, and forms 
o-alts with the alkalies, called molT/bdates. 

This acid is composed of 1 proportion of molybdenum 48, 
and 3 proportions of oxygen 24. 

TUNGSTEN 96. 

The tungstate of iron, is a brownish black mineral, which 
IS found both massive and crystallized. Its specific gravity 
is upwards of 7, and when broken it presents a foliated struc 
ture, and a lustre somewhat metallic. 

This mineral, by the miners, is called wolfram, and is com- 
posed of timgstic acid and oxide of iron, with a portion of the 
oxide of laanganese. 



How is the native sulphuret of molybdenum described 1 By what process is molybdic 
i acid procured 1 How is the metal obtained from this acidi What is the appearance of 
'i molybdenum? What are the salts called which molybdic acid forms with the salifiable 
bases 7 What is the appearance of tungstate of iron 1 How is tuogstic acid procured 7 
2'^ 



254 METALS. 

From this mineral the tungstic acid may be procured by the 
action of muriatic acid in the form of a yellow powder. 

When tungstic acid is mixed with charcoal, and exposed 
to an intense heat, the metal is deprived of its oxygen by the 
charcoal, and appears in its pure form. 

Tungsten has a specific gravity of 17.4 being next to pla- 
tina, gold, and iridium, the most dense body known. It is 
nearly equal to steel in hardness, and is one of the most infu- 
sible of the metals. When heated in the open air, it is recon- 
verted into tungstic acid. This acid is composed of 96 parts 
of tungsten and 24 parts of oxygen, consequently 96 is the 
atomic weight of this metal, and 1 20 the equivalent number 
for tungstic acid. No use has been made of this metal, or any 
of its compounds. 

coli;mbiu3I — 144. 

This metal was discovered by Mr. Hatchett of London, m 
a black mineral, which was sent to the British Museum by 
Gov. Winthrop, of Connecticut. The mineral came from 
New London, and is said to have been found near the resi- 
dence of the governor. 

Columbium, like tungsten, exists in its natural state, com- 
bined with so much oxygen as to perform the part of an acid, 
and is found united to the oxides of iron, or manganese. 

This metal is of an iron gray color, and considerable me- 
tallic lustre. Its specific gravity is 5,5 • 

Columbic acid is composed of columbium 144, and oxy- 
gen 8. Its equivalent number, therefore, is 152. 

ANTIMONY 44. 

The only ore from which the antimony of commerce is ob- 
tained, is the sulphuret. From this native compound the pure 
metal is separated, by heating it with half its weight of iron 
filings in a covered vessel. By this process the sulphur unites 
with the iron, while the fused antimony is drawn ofiT at the 
bottom of the vessel. 



What is the process for procuring tungsten from tungstic acid 1 What is the specific 
gravity of tungsten"? What are the properties of tungsten 1 What is the composition of 
tungstic acid 1 Whence came the mineral in which columbium was first discovered 7 
m what state does columbium exist combined with iron? Wiiat is the specific gravity 
of columbium 1 What is the ore from which antimony is obtained 1 In what mannei 
is this metal obtained from \ta ore 1 



MKTALS. 255 

Antimony is a brittle metal, of a bluish white color, and 
considerable lustre. Its structure is lamellated, or it consists 
of layers, which are the result of an imperfect crystallization. 
It fuses at about 800^, and when slowly cooled, may be crys- 
tallized in octohedrons. By exposure to the air it tarnishes, 
though not so readily as several other metals. Its specific 
gravity is about 7. 

ANTIMONY AND OXYGEN. 

Oxygen combines with antimony in three proportions, 
forming the protoxide, composed of antimony 44, and oxygen 
8 — the deutoxide, consisting of antimony 44, and oxygen 12 
and the peroxide, composed of antimony 44, and oxygen 16 

The deutoxide combines with alkalies, and forms salts ; it 
fe therefore called anilmonious acid, and the salts so formed 
are antimonitcs. 

The peroxide also performs the office of an acid, and com- 
bines with alkalies, forming salts, called aniimoniates, the acid 
itself being the a/Uimonic. 

Formerly, there were at least forty different preparations 
of antimony, known and used in medicine. At present this 
number is reduced to three or four, and of these only one is 
in general use, viz., the tartrate of antimony and potassa, or 
tartar emetic. 

ANTIMONY AND SULPHUR. 

The native sulphuret of antimony, as stated above, is the 
only ore from which the metal is extracted. This is gene- 
rally found in compact masses, though it sometimes occurs in 
long crystals, interlacing each other. It is of a leaden gray 
color, with a metallic lustre. 

The same compound may be formed by fusing antimony 
and sulphur together, or by transmitting sulphuretted hydro- 
gen through a solution of tartar emetic. 

Sulphuret of antimony is composed of 

Antimony 1 proportion, 44 
Sulphur 1 proportion, 16 



What is the cc^or and what the specific gravity of antimony 1 In how many propor- 
tions does oxygen combine with antimony 1 What are the oxides called 7 What is thd 
««Tirapasitioii of sulphuret of antimony t 



256 iMETALS. 



URANIUM 208. 



This metal was first detected in a mineral found in Saxony, 
which, from its black color, was called 'pitchblende. This 
ore, now called black oxide of uranium, contains uranium m 
ihe state of an oxide, mixed with the oxides of iron and lead. 

The metal is reduced from its oxide to the metallic state, 
with great difficulty, even in the laboratory of the chemist. 
According to Klaproth, \vho discovered it, uranium is of a 
dark gray color, with a metallic lustre, and granular texture. 
It is soluble in nitric acid, fuses only at the highest tempera- 
ture, and affords a deep orange color to enamel. Its specific 
gravity is about 8. 

Chemists are acquainted w^ith two oxides of this metal. 
The protoxide is composed of uranium 208, and oxygen 8. 
The combining number of the protoxide is therefore 2 1 6. 

The peroxide consists of 1 proportion of uranium 208, and 
2 proportions of oxygen 16; so that the equivalent number 
for the peroxide is 224. 

The protoxide occurs as a natural product, of a dark eme- 
rald green color, and shining lustre. lo is often found at- 
tached to other minerals, in the form of scales, or in bundles 
of crystals, variously grouped, or interlacing each other, af- 
fording one of the most beautiful products of the mineral king- 
dom. This oxide is also formed by art, and is employed to 
give a black color to porcelain, the change from green to 
black being produced by the heat of the porcelain furnace. 

CERIUM 50. 

The chemists have proved that a metal called cerium exists 
in a reddish brown mineral found in Sweden, and called 
cerite, or siliceous oxide of cerium ; and also in a mineral 
found in West Greenland, and called Allanite. 

The properties of this metal are little known, it having 
never been obtained, except in minute quantities, not larger 
than a pin's head. 

It has, however, been ascertained, that cerium combines 
with oxygen in two proportions, and that its combining or 



What is the ore ol uranium called ? What is the appearance of uranium 1 What is 
us specific gravity ? How many oxides of this metal are known? What is said of the 
native protoxide of this metal 1 What use is made of this oxide 1 What is said of the 
existence of the metal cerium 1 



MfiTALU 257 

equivalent number is 50. These oxides are composed of 
cerium 50, and oxygen 8, forming- the protoxide, whose equi- 
\'alent, therefore, is 58. The deutoxide contains the same 
quantity of metal, with one and a half proportions ofoxygen. 
Its equivalent is, therefore, 62. 

COBALT. 

The ore from which this metal is extracted, is called arse- 
nical cobalt. It is found in primitive rocks, both disseminated 
and in veins, associated with nickel, silver, bismuth, arsenic, 
and copper. 

When this ore of cobalt is heated in contact with the air, 
the arsenic is expelled in the form of arsenious acid, and the 
sulphur which it also contains is converted into sulphureous 
acid gas, and escapes. By this process, the ore commonly 
loses more than half its weight, and there remains in the fur- 
nace an impure oxide of cobalt, called zaffree. 

When zaffree is heated with sand and potash, there is form- 
ed a glass of a beautiful blue color, which, when pulverized, 
is extensively known and used under the name of smalt. The 
blue color of porcelain and earthenware, is produced entire- 
ly by this oxide of cobalt. Paper and linen, also, receive 
their bluish tinge from this oxide. 

From the oxide of cobalt, or zaffree, the metal may be ob- 
tained by heating that substance in contact with some carbona- 
ceous matter. If it is intended to obtain the metal in its pure 
state, the zaffree must first be purified from the iron, or other 
metals, which it may contain. 

Cobalt is a brittle metal, of a reddish brown color, and 
slightly metallic lustre. It is fused with difficulty. Its spe- 
cific gravity is 8.5. It is attracted by the magnet, and is ca- 
pable of being permanently magnetic. Muriatic or sulphu- 
ric acid acts but slightly on this metal, but it is readily solu- 
[ bie in nitric acid. 

! Cobalt does not attract oxygen by exposure to the air, but 
I by a long continued and strong heat, it is converted into an 
i oxide of a deep blue or nearly black color. The atomic 
i weight of cobalt has not been determined. 



What is said of the oxides of cerium? From What ore is the metaS cobalt obtained t 
What is zaffree 7 What is smalt 1 What is the use of oxide of coballt How may me- 
tallic cobalt be procured from the oxide 1 What is the appearance of cobalt? What is 
the specific gravity of cobalt 'I What is said of the magnetic property of cobalt 1 Whal 
acid is the proper solvent of cobalt 1 

22* 



25S METAL?. 

This metal is the base of that curious liquid called sympa 
thetic ink, and which may be prepared in the following man- 
ner : 

Dissolve one part of cobalt, or zaffree, in four parts oi 
nitric acid, and assist the solution by heat. To this solution 
add one part muriate of soda, and four times as much water 
as there was acid. 

Characters written on paper, with this ink, are illegible 
when the paper is cold, but become plain, and of a beautiful 
green color, when the paper is warmed. This experiment 
is rendered still more pleasant by drawing the trunk and 
branches of a tree, in the ordinary manner, and then tracing 
the leaves with the solution of cobalt. In winter such a tree 
will appear without leaves, except when warmed, but in the 
summer, particularly if placed in the sun, it will be covered 
with beautiful green foilage. Screens, painted w^ith this so- 
lution, will show their green when in use, but will immedi- 
ately begin to fade when carried away from the fire. 

NICKEL — 40. 

Nickel is generally found mineralized by the acids of 
arsenic. The Saxon ores, among which this metal is found, 
are mixtures of lead, copper, iron, cobalt, and arsenic, com- 
bined with sulphur and oxygen. In nearly every instance, 
where meteoric iron, or other meteoric products, have been 
analyzed, they have been found to contain this metal. 

Nickel, being of no use in the arts, is never reduced to its 
metallic state, except in the laboratories of chemists, as spe- 
cimens or curiosities. 

Nickel has a strong metallic lustre, and is nearly the color 
of tin and silver. It is both ductile and malleable, and like 
iron and cobalt, is attracted by the magnet, and may be made 
permanently magnetic. Its specific gravity, after being ham- 
mered, is 9. It is exceedingly infusible, and suffers no 
change at common temperatures, Avhen exposed to the air ; 
out is slowly oxidized at a red heat. The muriatic and sul- 
phuric acids do not act on nickel, but it is readily oxidized 
and dissolved in nitric acid. 



What is the method of preparing sympathetic iiik ? What are the peciUiar properties 
of this ink 7 With what is nickel combined in the natureil state 1 What is iaid of the 
existence o^ nickel in meteoric products ? Is this metal of any use in tlie aits ? \Vhai 
js the appeai-ance of nickel ? What is said of its magnetic property 7 What is its spa 
cific gravity "? In what acid docs nickel dissolve ] 



METAL$. 259 

Nickel combines with two proportions of oxygen. The 
protoxide is composed of nickel 48, and oxygen 8. The per- 
oxide of nickel 40, and oxygen 16. 

BISMUTH 72. 

Bismuth occurs native, and in combination with sulphur, 
oxygen, and arsenic. That which is employed in the arts 
and in commerce, is deriyed chiefly from the natiye metal. 
Bismuth has a reddish white color, a brilliant lustre, and a 
foliated structure. It fuses at 476^, being, with the exception 
of tin, the most fusible of the solid metals. When slowly 
cooled, this metal may be obtained in octohedial crystals. Its 
specific gravity is 10. 

Bismuth enters into the composition of printing type ; and 
its oxides are employed as paints, and in medicine. 

BISMUTH AND OXYGEN. 

Oxide of Bismuth — 80. 

1 p. Bismuth 72+1 p- Oxygen 8. 

Flowers of Bismuth. 

Bismuth combines w'ith oxygen in only one proportion, 
forming a yellowish vyhite oxide. This may readily be 
formed by submitting the metal to a strong heat in the open 
air. It takes fire and burns wdth a blue flame, while the 
oxide falls down in the form of powder. 

Bismuth is not readily soluble in the muriatic or sulphuric 
acids, but the nitric acid dissolves it with facility, forming 
nitrate of bismuth. 

When nitrate of bismuth, either in crystals or in solution, 
is thrown into water, a copious precipitate subsides, in the 
form of a beautifully white powder. This is the suhnitrate 
of bismuth, and was formerly knovyn under the name of 
ma gist ery of bismuth. This is emploA^ed as a cosmetic pow- 
der for whitening the complexion, but it is a dangerous sub- 
stance for such a purpose, since, if it happens to be exposed 
to sulphuretted hydrogen, it turns black, thus exposing the 
wearer to mortification and detection. 



What are the states in which bismuth is found 7 \Vhat is the color of bismuth t 
What are the uses of bismuth ) In how many proportions does this metal combin« 
with oxygen 7 Hew may this oxide be .ormsd"? What use is made of the subnitrata 
9f ^smuth 1 



260 METALS. 

TITANIUM, 

Titanium has hardly been seen in its pure metallic state, 
but the analysis of its oxides proves that such a metal exists. 

The ores of this metal are considerably numerous, and are 
widely disseminated. The native oxides of titanium some- 
times occur in long striated, acicular crystals, of a reddish 
brown color, and shining metallic lustre. Such crystals are 
sometimes contained in transparent pieces of quartz, forming 
specimens of singular beauty. 

The artificial oxides of this metal are white, and are ob- 
tained by difficult processes. They hold their oxygen with 
such tenacity that all attempts to reduce them, by means of 
heat and a combustible, in the usual manner, have failed. 

The equiv^alent numbers of these acids have not been deter 
mined with certainty. 

TELLURIUM 32. 

This is an exceedingly rar# metal, being hitherto found 
only in the gold mines of Transylvania, and at Huntington* 
in Connecticut. It occurs in the metallic state, associated 
with gold and silver, lead, iron, and sulphur. The color of 
tellurium is between these of zinc and lead ; texture lamina- 
ted, like that of antimony, which it also resembles in some of 
its properties. It melts at about 600° ; has a specific gravity 
of 6. 1 1 ; is brittle, and easily reduced to powder. When 
heated before the blowpipe, it takes fire, burns rapidly with a 
blue flame, and is dissipated in gray fumes, which are an 
oxide of the metal. 

This oxide, which is the only one tellurium forms, is com 
posed of 32 parts of this metal and 8 parts of oxygen ; so thai 
32 is the atomic weight of tellurium, and 40 the equivalent of 
its oxide. 

COPPER — 64. ' 

Copper is found native, also combined with sulphur, with 
oxygen, with carbonic acid, arsenic acid, sulphuric acid, mu 
riatic acid, and with several of the metals. Its ores are very 
numerous, and some of them highly beautiful and interesting 



What is said of tlie existence of titanium 7 What is said of the native oxide of tita- 
nium 1 Where have the ores of tellurium been found 1 In what state does tellurium 
occur? What is the color of tellurium 1 What is the composition of the oxides of t^ 
liirium T What are the fiubstancee with which copper is found combined 1 



METALS. 261 

The uses of this metal are numerous, and well known. In 
the metallic state, it forms a part of brass, of pinchbeck, of 
Dutch gold, and many other alloys. 

When dissolved in various acids, it forms compounds which 
are employed for a great variety of useful purposes. 

The green pigment, verditer, is a nitrate of copper, preci- 
pitated by carbonate of lime. Verdigris is an acetate of cop- 
per. Mineral green is a sulphate of copper, precipitated by 
caustic potash. 

Copper receives a considerable lustre by polishing, but 
soon tarnishes when exposed to the open air. Its specific 
gravity is 8.78, and is increased by hammering. It is mallea- 
ble and ductile, and its tenacity is inferior only to iron. It 
hardens when heated and suddenly cooled. At a red heat, 
with access of air, it absorbs oxygen, and is converted into 
the peroxide, which appears in the form of black scales. 

Nitric acid acts on this metal with vehemence, and it is 
dissolved slo^vly in the muriatic and sulphuric acids. The 
vegetable acids, as vinegar, also dissolve copper when ex- 
posed to the air, but not otherwise, the oxygen of the atmos- 
phere assisting in the oxidation of the metal. 

COPPER AND OXYGEN. 

Protoxide of Copper — 72. 
1 p. Copper 64+1 p. Oxygen 8. 

Red Oxide of Copper. 

The red, or protoxide of copper, is found native in the form 
of regular octohedral crystals, variously truncated, and form- 
ing specimens of great beauty. It may also be prepared ar- 
tificially, by mixing 64 parts of copper filings with 80 parts 
of the peroxide in powder, and heating the mixture to redness 
in a close vessel. By this process, the copper filings attract 
one proportion of oxygen from the peroxide, which contains 
twdce the quantity of oxygen contained in the protoxide. 
Thus the quantity of oxygen is equalized, and the ^vhole is 
converted into the protoxide. 

This experiment affords a very simple illustration of the 
law of definite proportions. Eighty parts of the peroxide of 



What are the principal uses of copper 7 What is the specific gravity of copper 1 
; How may copper be converted into a peroxide ? What acids dissolve this mrtal? In 
what form does the protoxide of copper occur 1 How may the protoxide of copper la 
piepaied by art 1 



262 METALS. 

copper contains 64 parts of the metal, and 16 of oxygen. 
When this quantity is heated with 64 parts of copper, 1 pro- 
portion, or 8 parts of oxygen, leaves the peroxide, and unites 
with the copper, thus making, in the whole, 144 parts of the 
protoxide, the copper gaining 8, and the peroxide losing 8, 
the number for each becomes 72, the equivalent for the prot 
oxide 

Peroxide of Copper — 80. 
1 p. Copper 64+2 p. Oxygen 16. 

This oxide is said to be found in the native state. By art, 
it may be formed by keeping thin pieces of copper at a red 
heat exposed to the air, or by heating the nitrate of copper to 
redness. 

This oxide is dark brown, or nearly black. When heated 
alone, it undergoes no change, but if heated in a close vessel, 
with charcoal, or other combustible, it parts with the whole 
of its oxygen, and is reduced to the metallic state. It com- 
bines Avith most of the acids, and produces salts of a green 
or blue color. 

Copper combines with sulphur, and forms a sulphuret of 
the metal. This compound occurs native, and may be formed 
by heating a mixture of copper filings and sulphur. It is 
composed of 64 parts of the metal and 16 of sulphur. 

LEAD — 104. 

In a few instances lead has been found in the native state ; 
but it most commonly occurs combined with sulphur, form- 
ing the sulphuret, of a bluish gray color, and strong metallic 
lustre. This compound is known under the name of galena, 
and is the ore from which the lead of commerce is exclusively 
obtained. 

The color and common properties of lead are well known. 
Its specific gravity is 11. In tenacity, it is inferior to all the 
ductile metals. It fuses at about 600° and when slowly 
cooled, may be obtained m octohedral crystals. When newly 



Explain how the process for forming the protoxide of copper illustrates the law of defi- 
nite proportions. How may the peroxide of copper be formed 1 How may the peroxide 
of copper be reduced to the metallic state 7 What is the composition of the sulphuret of 
T pper 7 In what state is lead chiefly found 1 What is the common name for sulphuret 
©f lead ? What is the pj^f.cific gravity of lead 1 



METALS. 263 

cut, il has a brilliant metallic lustre, but is soon tarnished by 
exposure to the air. 

Lead is not oxidized by moisture without the contact of air, 
and hence it may be kept under pure water, for any length of 
time, without change. But if water be placed in an open ves- 
sel of lead, the metal is slowly oxidized, and a white crust is 
formed, at the points of contact between the lead, water, and 
air, which is a carbonate of the protoxide of lead. Hence, as 
the salts of this metal are poisonous, leaden vessels open to the 
air, should never be employed to contain water for culinary 
purposes. 

The sulphuric and muriatic acids act slowly upon this me- 
tal. Concentrated sulphuric acid produces so little action on 
it, that the acid is made in chambers lined with lead. Nitric 
acid is tJie ])roper solvent of this metal. The solution, w^hen 
evaporated, deposits whitish opaque crystals of nitrate of 
lead. 

LEAD AND OXYGEN. 

There are three oxides of lead, w^hich are thus constituted : 

Lead. < }xygen. 

Protoxide, 104 + 8 -= 112 

Deutoxide, 104 + 12 == 116 

Peroxide, 104 + 16 = 120 

Protoxide of Lead. — This oxide is procured in purity, 
when a solution of the metal in nitric acid is precipitated by 
potash, and the precipitate dried. It is of a yellow color ; is 
insoluble in Avater, and fuses at a red heat. The same oxide 
is formed by heating lead in the open air, and is known in 
commerce by the name of massicot. When massicot is par- 
tially fused, in contact with the air, it becomes of a reddish 
color, and is known by the name of litharge. This appears 
to be a mixture of the protoxide and deutoxide of lead. Li- 
tharge is mixed with oil used in painting, in order to make it 
dry more rapidly. It is probable that this effect is produced 
by the oxygen, which the litharge imparts to the oil. 

The well known pigment called ivhite lead, is a carbonate 
of the protoxide. This substance is prepared by placing rolls 
of thin sheet lead in pots containing vinegar. The vinegar 



W\i2X is said of the oxidation of lead when kept under water ? Under what circum- 
stances does water become poisonous, when kept in leaden vessels ? AVhat is said of the 
action of different acids on lead? How many oxides of lead are there, and what is the 
composition of each 1 Wliat is maesicot ? How is litharge prepared 7 What is the use 
©f litharge 1 



264 METALS. 

imparts its oxygen to the metal gradually, and probably pre 
pares it for the absorption of carbonic acid from the atmos 
phere. Or possibly the lead may be dissolved by the acetic 
acid, and this acetate in its forming state decomposed by the 
carbonic acid of the atmosphere, in the same manner that the 
chloride of lime is decomposed, and changed into a carbonate 
by exposure to the air. White lead was formerly considered 
a peculiar oxide, but analysis shows that it is a compound of 
ihe yellow oxide, and carbonic acid. 

Deutoxide of Lead. — This is the red lead of commerce, ana 
is extensively used as a pigment, and in the manufacture of 
flint glass. It is formed by heating litharge in a furnace so 
constructed that a current of air constantly passes over its 
surface. In this manner, the litharge, which is chiefly a prot- 
oxide, is converted into a deutoxide, by absorbing another, 
proportion of oxygen from the air. 

When red lead is heated to redness, it gives off pure oxy- 
gen, and is reconverted into the deutoxide. 

Peroxide of Lead. — This is formed by the action of nitric 
acid on red lead. The red lead, or deutoxide, is decom- 
posed by the acid, and resolved in the protoxide which it dis- 
solves, and converts into the peroxide, which being insoluble, 
falls down in the form of a puce colored powder. This ox- 
ide is insoluble in any of the acids. When heated it gives 
off large quantities of oxygen gas, and Is resolved into the 
protoxide. 

Sulphuret of Lead. — This compound occurs very abun- 
dantly as a natural product, and may be formed by fusing ? 
mixture of lead and sulphur. 

The lead of commerce, as above stated, is obtained exclu- 
sively from this ore, which is generally known under the 
name of galena. The metallic lead is easily obtained from 
the sulphaiet. The ore being placed in the furnace, is gradu- 
ally heated vv^th small Vv^ood or faggots, to drive off the sal- 
phui. Alter wards, charcoal and lime are thrown in, and 
the hegj is mcreased. As some portions of the lead become 
oxidated by exposure to the air and heat, the charcoal redu- 
ces these portions by the absorption of their oxygen, and at 
the same time mcreases the heat. The lime combines with 



"What is the composition of white lead? How \a white lead prepared 1 What is the 
deutoxide of lead 1 IJow is red lead prepared, and what is its use ? What proportion o< 
oxygen does the deutoxide contain 7 How is the peroxide of lead formed 1 What r7e the 
Vroperiies of the peroxide of lead ? How is lead rpduced from the <ji.'lphvra ^- 



Metals. 26S 

the sulphuric acid, which is formed by the union of the sul- 
phur of the metal, the oxygen of the air, and the water of the 
wood, and forms a sulphate of lime. Meantime, the metallic 
lead, thus reduced, runs down into the lower part of the fur- 
nace, where it is drawn off into proper vessels. 

All the salts of lead act as poisons, with the exception 
of the sulphate, which Oriila has proved is not deleterious. 
The same author has shown that the acetate, or sugar of 
lead, is decomposed in the stomach by sulphate of magnesia 
or Epsom salt, and that the inert sulphate is thus formed. 
Hence, Epsom salt, or Glauber's salt, which is a sulphate of 
soda, becomes an antidote to the poisonous effects of sugar of 
le^d when taken soon after it. 

SALTS. 

The compound resulting from the union of any acid with 
an alkali, an earth, or a metallic oxide, in definite propor- 
tions, is called a salt. 

The substance which combines with the acid to form the 
salt, is called the base. Thus, lime is the base of carbonate 
of lime. Any substance capable of combining with an acid 
to form a salt, is called a salifiable base. The salifiable 
bases, therefore, are the alkalies, the earths, and metallic 
oxides. 

Any compound, which is capable of uniting in definite pro- 
portions with a salifiable base, or which in solution is sour 
to the taste, or reddens vegetable blues, is an acid. 

From this definition, it will be observed that acids are not 
necessarily sour to the taste. This, in many instances, arises 
from their insolubility, for an insoluble acid neither tastes 
sour, nor changes the color of vegetable blues. Other acids, 
which, though soluble, do not taste sour, and have little, if 
any action on colors, still have the property of neutralizing 
alkalies, and combining with salifiable bases in definite pro- 
portions ; such is the prussic acid. 

It was form.erly supposed that all the acids contained oxy* 



What are the uses of charcoal and lime in the reduction of lead 7 Wliat compound of 
lead is said to be poisonous 1 What antidote is mentioned to the poisonous effects of sugar 
of lead 1 How does Epsom salt act to neutrallize the poisonous effects of the salts qf 
lead 1 What is a salt 7 What is the base of a salt 1 What is a salifiable base 7 WhaX 
is an dcid7 Are all acids sour to the taste 1 Do all acids contain oxygen 1 

23 



266 SALTS. 

geiL as the acidifying principle, but we have already had 
occasion to remark, that there are several known excepdona 
to this truth. Since the discovery of the compound nature 
of the alkalies, and the simple nature of chlorine, it is found 
that some compounds, in which oxygen exists as an elemenl 
are alkalies, and that others, containing no oxygen, are acida 
Thus, the metal potassium, combined with oxygen, forms the 
alkali potassa, and chlorine, united to hydrogen, forms mu- 
riatic acii 

The alkalies are supposed to possess characters exactly 
opposite to those of the acids. Their tastes are pungent; 
they neutralize the acids, and change vegetable blue colore 
to green. There are, however, many compounds, capable ^f } 
forming salts, and of neutralizing acids, which do not possese \ 
the latter characters. Thus magnesia, though a powerfiil 
neutralizing substance, excites no taste, and produces littfe; 
change on vegetable colors. This want of action obviously V 
depends on its insolubility in water. 

Thus, a saliliable base does not necessarily contain sensh 
ble alkaline properties, but is any substance which forms » 
dennite compo^ond with acids, or which being soluble, hat < 
the alkaline taste, and changes vegetable blues to green. Ah" 
the metainc oxides are saliliable bases. 

In speaking of the solution of a metal in an acii it miu» 
always be understood, that it is the oxide of the metal which ■ 
is soluble, for no metal combines with an acid in its metallic i 
stare. The action of the acid is first to oxidate the metal; 
which it does, either by imparting to it a portion of its own 
oxygen, or by assisting it to obtain this principle from, the 
water with which the acid is mi:«^Gi When copper diisoivea 
in nitric acid, the metal is nrM oxidated at the expense of 
one proponion of the oxygen which the acid contains, and 
hence the fimies of nitrous gas which escape. But when 
zinc dissolves in dilute sulphuric acid the metal is oxidated 
by the decomposition of the water, and then dissolved by the 
acid, and hence the escape of hydrogen during this procesa. 



Do the ar^alips anitalu Qzrgsn ? GLre an iziauiice where axTgeo, combined vuhsj 
metal ibnos an alkalL Gire an instance in which chlorinft and anodier annpie sob 
united, fenn an acid. Whr is m^nesa tastefeas ? Are the metalfic oxides aa]ifidblr| 
si What change do the metals nndeiso b^bce ther are aohriiie in the acids 1 
do the metalB become ooddes befcre diey are dJBBotved 1 Wheel 
I mio dBaied a^dpfanric acid, whj does hydrogen oweape 1 



SALTS. 20''' 

Ii is said that al least 2000 salts are known, but thi5 is a 
small number when compared with those which might be 
formed ; for supposing each acid to be capable of forming a 
different compound ^vith each salifiable base, and each base 
* a distinct compound with every known acid, the salts would 
De numberless. 

It may be supposed, from the variety of properties pos- 
sessed by the acids, that the salifiable bases, with which 
ihey are knoT\Ti to combine, that the resulting compounds 
must present a great variety of different qualities, colors, and 
shapes, and in this we are not disappointed Some of the 
/s are corrosive poisons, others are perfectly inactive on 
.^'j animal system; some are used as medicines, others as 
'paints, others in coloring, &c. 

It is obvious that in this epitome of the science, only a 
limited number of these compounds can be described. 
These we shall arrange in groups, or classes, each group 
consisting of the same acid, united to different salifiable 

: of the salts are capable of being cr^'stallized, that is, 

.:ng dry sobd figures of determinate shapes. During 

iijL of cr}'Stallization, many of them combine chemically 

:a a definite portion of water, which therefore is called the 

^er of crystallizoAion. 

Some salts contain more than half their weight of water; 

i is the case with sulphate of soda, or Glauber's salt, which 

^*.^'s of 72 parts of the dry sulphate, and 90 pans of 

:r salts, as muriate of soda, or common salt, contain 

rr of crv'stallization. But these salts sometimes con 

:'' water included mechanically within their 

..ence when heated they decrejpitoAe, or fiy in 

:es, m consequence of the conversion oi this water into 

:in. From this cause, common salt decrepitates violently 

en thrown on the fire. 

-Salts containing a large quantity of the water of crystal* 
-tion, when heated, undergo the o.queous fusion ; that is, 
V dissolve in the water they contain. Anhydrous salts, 
iuch as are not chemically united with water, when heat 



On vrha: principle fj-e ::.-. salu; -.l.rowp 
:. 7 Do >::.±c. sails -i':=iJi t^'^.^z oi 



268 SALTS. 

ed, undergo the igneous fusion. A salt is said to effl.ortsc'., 
when its water of crystallization evaporates, and it falls into 
a dry powder. 

Most of the salts are soluble in water ; and with a feAv ex- 
ceptions, the solvent power of this fluid is in proportion to its 
temperature. One of these exceptions is common salt, which 
is equally soluble in cold and hot water. Some of the salts 
require 500 or 600 times their own weight of water for so- 
lution. This is the case with carbonate of lime, and sulphate 
of lime. In a few instances, as in the sulphate of baryta, 
the salts are entirely insoluble in water. On the contrar}'-, 
some of these compounds have such an affinity for water, as 
to enter into solution with that which they attract from the 
atmosphere. In these instances the salt is said to deliquesce. 
Muriate of lime is an example. It cannot be kept in the solid 
state, unless closely excluded from the atmosphere. 

All the salts are composed of definite proportions of their 
ingredients, and these ingredients are compounded of defi- 
nite proportions of elementary bodies. Thus, sulphate of 
potash is composed of 40 parts of sulphuric acid, and 48 
parts of potash. The acid is composed of 16 pans, or 1 atom 
of sulphur, and 24 parts, or 3 atoms of oxygen. Potash is 
composed of 40 parts, or 1 atom of potassium, and 8 parts, or 
1 atom of oxygen. 

Thus the salts are formed by the union of compound sub- 
stances, and their equivalent numbers are the sums of the 
atomic weights of these substances. Thus, the equivalent 
number for the sulphate of potash is 88, being composed o\ 
the equivalents for sulphuric acid 40, and the equivalent for 
potash, 48. How these latter numbers are obtained has just 
been explained ; and indeed the whole of the above, so far as 
regards definite proportions, is only a recapitulation of what 
has already been stated more in detail, in its proper place; 
but is repeated here, because the doctrine of proportions ap- 
plies especially to the composition of the class of compounds 
which we are now about to describe. 

Some salts combine with each other and form compounds, 
which were formerly known under the name of triple salts. 



When is a salt said to effloresce 1 What salt is equally soluble in cold and hot watery 
What salts require a large portion of water for solution'? When is a salt said to deli- 
quesce 1 What is said of the definite proportions of the ingredients and elements of iW 
ealts 1 What is the composition of sulphate of potash 1 How is the equivalent numb*«t 
for sulphate of potash obtained 1 



BULPHATBS. 269 

But as, m these instances, only two bases combine with one 
acid, or two acids with one base, this kind of union is more 
properly indicated by the term double than triple ; and this 
change being proposed by Berzelius, is now employed by 
recent writers. 

In describing the salts, we shall follow the method already 
observed in respect to other compounds, and place the equiv 
ulent numbers at the head of each description. 

SULPHATES. 

The sulphates, when heated to redness with charcoal, are 
decomposed and changed into sulphurets. The oxygen, both 
of the oxide and the acid of which the salt is composed, 
unites with the carbon, forming carbonic acid, w^hile the sul- 
phur and metal combine to form the new compound, the sul- 
phuret. 

The sulphates in solution, are readily detected by muriate 
of baryta ; the muriate being decomposed by the sulphuric 
acid, an insoluble sulphate of bar3rta is formed, which falls 
to the bottom of the vessel in the form of a white powder. 

Several sulphates exist in nature, the most abundant of 
which are those of lime and baryta. The sulphate of lime 
is very abundant in some countries, and is employed as a 
manure, and in the arts, under the name of gypsum or plaster 
of Paris. 

Sulphate of Pctassa — 88. 

1 p. S. Acid 40+1 p. Potassa 48. 

Vitriolated Tartar, 

This salt is prepared by decomposing the carbonate of pot- 
ash with sulphuric acid. Its crystals are in the form of six- 
sided prisms terminating in six-sided pyramids. Its taste is 
saline and bitter. This salt suffers no change on exposure 
to the air. Its crystals contain no water of crystallization, 
land when thrown on the fire, decrepitate for the reason for- 
merly explained. These crystals are soluble in 16 times 
their weight of water at 60 degrees. 

The composition and equivalent number of this salt are 
seen above. 



What is meant by a double salt? How are the sulphates changed into sulphurets 1 
in what manner does the charcoal and heat change sulphates to sulphurets? How doea 
Tiuriate of barytes show the presence of sulphuric acid? How is sulphate of potash 
bnned i What is the composition and equivalent number of this salt H 

23* 



270 SULPHATES. 

Sulphate of Soda — 72. 

1 p. S. Acid 40+1 p. Soda 32. 

Glaubers Salt. 

Sulphate of soda sometimes occurs as a native compouTiJ, 
and may be readily formed by saturating common carbonate 
of soda by dilute sulphuric acid. That sold by apothecaries 
is chiefly prepared from the contents of the retort after the 
distillation of muriatic acid. 

This acid is obtained by distilling a mixture of common 
salt, and sulphuric acid. The latter acid, combining with 
the soda of the muriate, the muriatic acid is evolved and sul- 
phate of soda formed. This being purified, forms the Glau- 
ber's salt of commerce. 

Sulphate of soda crystallizes in four and six-sided prisms. 
These crystals when exposed to the air, part with their 
water of crystallization, or effloresce, leaving the salt in the 
state of a dry powder. By this process the salt loses about 
half its weight. 

According to the analysis of Berzelius, this salt contains 
72 parts of the neutral sulphate, and 90 parts, or ten atoms 
of water. 

The combining proportions, or equivalents, of the salts, 
refer only to the acids and bases which they contain, and 
not to their water of crystallization. It is found, however, 
that the water of crystallization is always combined in definite 
proportions, as well as the other ingredients. The combining 
number for water, as already explained, is 9, and in the pre- 
sent instance the doctrine of multiple proportions by a whole 
number is found to be precisely true, there being 10 atoms, or 
proportions, of water in this salt. 

Sulphate of Baryta — 118. 
1 p. S. Acid 40+1 p. Baryta 78. 

Heavy Spar. 

The native sulphate of baryta is widely disseminated, 
though not often found in very large quantities at any one lo- 



What is the composition of sulphate of soda 1 \Miat is the common name of this saltl 
How is Glauber's salt prepared 7 What proportion of water does sulphate of soda con- 
tain 1 What is said of the definite quantity of the water of crystallization '? What is thd 
composition and equivalent number of sulphate of baryta 7 What is tlie common nam« 
of this salt 7 Is eulphate of baryta a native, or an artificial salt 7 



SULPHATES. 271 

cality. It occurs both massive and in anhydrous crystals, 
which arc generally flattened, or tabular. This substance 
is known under the name of heavy spar, having a specific 
gravity of nearly 42", being the most ponderous of earthy mi- 
nerals. 

It is formed artificially by mixing the earth baryta with 
sulphuric acid. 

It is the most insbolule of all the salts, and bears a strong 
heat without suffering any change. 

This substance is sometimes employed to form the solar 
phosphori, a compound which shines in the dark, after hav- 
ing been exposed to the light of the sun. 

It is prepared by first igniting the native sulphate, after 
which it is powdered and sifted. It is then mixed with mu- 
cilage of gum arabic and formed into cylinders about the 
fourth of an inch in thickness. These being dried in the sun, 
are exposed to the heat of a wind furnace supplied with char* 
coal, for about one hour, and the fire suffered to burn out. 
The cylinders will be found among the ashes retaining their 
original shapes, and must be preserved in a well stopped 
vial. 

When this substance is exposed for a while to the sun, and 
then carried into the dark, it will emit so much light as to 
show the hour by a watch dial. 

Sulphate of Lime — -68. 

1 p. S. Acid 40+1 p. Lime 28. 

Gypsum. Plaster of Paris, 

This salt occurs abundantly as a natural production. It is 
composed of 68 parts of the pure sulphate, and 18 parts or 
two proportions of water. This salt is found crystallized in 
broad foliated plates, and also in compact masses. It is 
ground, and spread on certain kinds of land as a manure. 
In this state it is called ground plaster. The compact vari- 
ety is called alabaster, and is cut, or turned into various or- 
namental articles, such as candlesticks, vases, and boxes. 
Some of these specimens are perfectly white, and being 



IIow is solar phosphori prepared from sulphate of baryta? What curious property has 

he solar phosphoms ? What is the composition of sulphate of lime 7 What quantity of 

, water does this salt contain 1 What is the common name for sulphate of lime 7 What 

; ire the uses of sulphate of lime 1 Wliat is the compact variety of this salt called 7 How 

s gypsum prepared to form stucco work 1 



r 



272 gULPHATES, 

translucent, are among the most beautiful productions of tlie 
mineral kingdom. Other varieties of this mineral are co- 
lored with metallic oxides, and present the appearance of 
clouds, stripes, or spots of red, blue, or brown, interspersed, 
or alternating with each other. 

Sulphate of lime is largely employed in forming the orna- 
mental, or stucco work, for churches and houses. For this 
purpose it is first heated nearly to redness, or as the workmen 
term it, boiled, in order to expel the water of crystallization, 
and then ground in a mill. In this state it is a fine white 
powder, which being mixed with water and cast into moulds 
of various figures, forms the ornamental Avork seen on the 
walls of churches and rooms. 

After being mixed with the water, it must be immediately 
poured into the mould, for however thin the paste may be, it 
grows hard, or as the workmen call it, sets, in a few minutes, 
and no addition of water will again make it as thin as before. 
This is owing to the chemical combination which takes place 
between the anhydrous sulphate and the water, and by which 
the latter is made solid. 

Sulphate of lime is soluble in about 500 parts of cold wa* 
ter, and as it exists abundantly in the earth, it is more fre- 
quently found dissolved in the water of w^ells and springs, 
than perhaps any other salt. When it exists in considerable 
quantity, it gives that quality to the water called hardness. 
Such water decomposes soap, by neutralizing its alk^Ji, and 
therefore is not fit for washing. 

Sulphate of Magnesia — 60. 

7 p. S. Acid 40+ 1 p. Magnesia 20. 

Epsom Salt, 

Epsom salt is sometimes obtained by evaporating ^he wa 
ter of springs which contain it in solution, and som^^times it 
is made artificially, by first dissolving magnesian limestone 
in vinegar, which takes up the lime and leaves the magnesia. 
The magnesia is then purified by calcination, and afterwards 
dissolved in dilute sulphuric acid, and crystallized by evapo- 
ration. 



What chemical change is produced when the anhydrous sulphate is mixed with water 7 
What is meant by anliydrous 1 What effect does sulphate of lime have on the water of 
weJIs? Vhat is the composition of sulphate of magnesia 1 What is the common name 
ofsulphatt Df magnesia? What is the use of this salt 7 How is sulphate of magnesia 
orei.>a.red 7 What is the common name of sulphate of alumma and potash / What is the 
composition of alum 1 



SULPHATES. 273 

This salt appears in minute quadrangular shining crystals. 
These suffer little chrnge when exposed to the air, undergo 
the watery fusion when heated, and are soluble in three 
fourths of their own weight of boiling water. Its use, as a 
medicine, is well known. 

Sulphate of magnesia is composed of 60 parts of the dry 
sulphate, and 63 parts, or 7 atoms of water. 

Sulphate of Alumina and Potassa — 262. 

3 p. Sulph. Alumina 174+1 p. Sulph. Potassa 88. 

Alum. 

Alum is a substance so well known, that its external ap- 
pearance requires no description. Its taste is at once astrin- 
gent and sweetish. It is soluble in about its own weight of 
boiling water. It crystallizes in octohedrons, or eight-sided 
figures, and, by peculiar management, these crystals may be 
obtained of great size and beauty. It is a double salt. 

Sometimes alum is found ready formed in earth or friable 
rocks, and is extracted by collecting such earth into proper 
vessels, and pouring on water, which, passing through, dis- 
solves, the salt and holds it in solution. The water being then 
evaporated, the alum shoots into crystals. 

When the mineral, which furnishes this salt, is aluminous 
clay, mixed w4th sulphur and iron, which is more often the 
case, another method is taken. The mineral being exposed 
to heat, or merely to the action of the air, the sulphur attracts 
oxygen, and is converted into sulphuric acid, which then com- 
bines with the alumina and forms a sulphate. If no potash 
be present in the earth, this is added, and the whole is treated 
by lixiviation, (that is, pouring on water until the salt is dis- 
solved,) and the liquid afterwards evaporated to obtain the 
alum. 

Alum is used in medicine and in the arts. Its composition 
IS stated at the head of this section. Alum is the base of a 
curious composition, called Homherg^s pyrophorus, w^hich 
ignites, on exposure to the air. It is prepared in the follow 
ing manner : 

Reduce an ounce or two of alum to powder, and mix it 
with an equal weight of brown sugar. Put the mixture into 



What is the process by which alum is obtained 1 What is the use of alum ? How is 
Homberg's pyrophorus prepared ? What singular and curious property does this com- 
lK)und possess? 



274 SULPHATES, 

an earthen dish, or ladle, and keep it stirring over the fire 
until all the moisture is expelled. Then, having pulverized 
it finely, introduce the powder into a common vial, coated with 
a mixture of clay and sand. To the mouth of the vial, lute a 
small glass tube, or the stem of a tobacco pipe, in order to 
allow the moisture and gases to escape. The vial, thus pre- 
pared, is set in a crucible, surrounded with sand, and the 
whole placed in a coal fire, and gradually heated to redness. 
At first, steam will issue from the tube, but afterwards a gas, 
which, being set on fire, burns with a blue flame. 

After the flame goes out, keep up the heat for about fifteen 
minutes, and then remove the crucible from the fire, and im- 
mediately stop the orifice of the tube with a piece of wet clay. 
When the vial is cool, pour its contents hastily into other 
vials, which are perfectly dry, and then cork them so as en- 
tirely to exclude the air. 

This compound resembles powdered charcoal in appear- 
ance ; but if a few grains be poured out, and exposed to the 
air, it soon glows with a red heat, and will set paper or wood 
on fire. If poured from the vial, at the distance of a few feet 
from the ground, it forms a shower of fire. When intro- 
duced into oxygen gas, it spontaneously explodes, giving out 
intense heat and light, and affording a very brilliant experi- 
ment. 

Small vials of this pyrophorus may be preserved for years, 
and may be made highly convenient, especially for itinerant 
smokers, and to those who are travelling through a wilder- 
ness. 

The ignition of this substance is caused by its strong a^ 
traction for the oxygen of the atmosphere. 

Sulphate of Iron— 76. 

1 p. Sulph. Acid 40+1 p. Oxide Iron 36. 

Copperas. Green Vitriol. 

This well known salt is the sulphate of the protoxide of iron, 

and may readily be formed by the action of dilute sulphuric 

acid on metallic iron. The green vitriol of commerce is, 

however, manufactured directly from the sulphuret of iron, 

which nature furnishes in abundance. For this purpose, the 

ore, being raised from the earth, is exposed to the air, and 



For what useful purpose may this pyrophorus be employed 1 Wliat is the composi 
tion of sulphate of iron 1 What is the common name of sulphate of iron 1 How j» 
green vitriol manufactured on a large scale 1 



NITRATES. 275 

occasionally sprinkled with water. By a natural process, the 
sulphur absorbs oxygen from the atmosphere, and is converted 
into sulphuric acid, which is retained by the water. The acid 
cnus formed, combines with the iron, forming a sulphate of 
the metal, which appears, on the decomposition of the ore, in 
a greenish crust. The mass is then lixiviated, or washed by 
pouring water through it, by which the salt is dissolved, and 
afterwards obtained in crystals by evaporating the water. 

Sulphate of iron is of a greenish color ; has an astrmgent 
metallic taste, and is soluble in three fourths of its weight of 
boiling water. According to the analysis of Berzelius, it con- 
tains 76 parts, or 1 equivalent of the sulphate, and 63 parts, 
or 7 atoms of water. 

Large quantities of this salt are employed in the arts, chief- 
ly for coloring black, and making ink. 

Sulphate of Zinc — 82. 

1 p. S. Acid 40+1 p. Ox. Zinc 42. 

White Vitriol. 

When diluted sulphuric acid is poured on zinc, for the pur- 

!)ose of obtaining hydrogen, the residue, if allowed to stand, 
brms small white crystals. This is the sulphate of zinc. 
For the purposes of commerce it is made by roasting the na- 
tive sulphuret of this metal, and then throwing it into w^ater. 
The sulphate is formed by the decomposition of the sulphu- 
ret, on the same principle as above described for the manu- 
facture of green vitriol, and being dissolved by the water, is 
obtained by evaporation. 

Sulphate of zinc has a strongly styptic taste, is soluble in 
about two and a half parts of cold w^ater, and reddens vegeta- 
ble blue colors, though strictly a neutral salt. 

This salt consists of 82 parts of the sulphate, and 7 atoms, 
or 63 parts of water. 

It is employed in medicine, as a tonic and emetic. 

NITRATES. 

The nitrates, when thrown on burning charcoal, deflagrate, 
i or produce a vivid combustion of the charcoal. This is in 



Explain the cberaical changes by which the sulphuret of iron is converted into cop- 
peras. What are the uses of sulphate of iron 7 Of what is sulphate of zinc composed 1 
, What is the common name of sulphate of zinc. How is the sulphate of zinc of com- 
\ merce prepared ? What proportion of water does this jalt contain 1 What arc th^ iisef 
8f white vitrijU 



276 NITRATES. 

consequence of the oxygen gas which they yield when hea: 
ed, which unites with the combustible as it is expelled. 

All the nitrates, without exception, are decomposed at hisfj 
temperatures, or by heat alone. Some of them, as the nitrat 
of potash, or nitre, yield oxygen gas in a state of considera 
ble purity when heated, and hence are employed for the pui 
pose of obtaining oxygen. 

As all the nitrates deflagrate when thrown on burning chai 
coal, this simple test is sufficient to distinguish them fron 
other salts. Another test of these salts, is their power of dis 
solving gold leaf, when mixed with muriatic acid. 

The only native nitrates are those of potash, lime, soda 
and magnesia. 

Nitrate of Potash — 102. 
1 p. N. Acid 54+1 p. Potash 48. 
Saltpetre. Nitre. 

This salt may be prepared by saturating the common car 
bonate of potash with diluted nitric acid, and evaporating th< 
solution until crystals are formed. 

That used in commerce, and for the manufacture of gun 
powder, is prepared by throv/ing into heaps, under cover, tin 
remains of decayed vegetable and animal matter, found abou 
old buildings. Heaps of such earth, when exposed to the aii 
under sheds, gradually generate nitric acid, in consequence 
of the combination of the nitrogen, which is always containec 
in animal remains, with the oxygen of the atmosphere. The 
earth from such situations also contains lime, magnesia, anc 
commonly, considerable proportions of potash, from the ashes 
of burned wood. Thus there appears to be formed in thest 
nitre beds, the nitrates of lime, potash, and magnesia. After 
the earth has remained in this situation for several months, 
being now and then sprinkled with water, is lixiviated, and 
to the solution of these salts there is added a quantity of pot- 
ash, which decompose the nitrates of lime and magnesia, thus 
leaving the nitrate of potash in solution. The nitre is then 
crystallized by evaporating the water, and afterwards further 
purified for use. 



Wliy do the nitrates deflagrate when thrown on burning charcoal 7 Wliat gas do the 
nitrates yield when heated 1 How may the nitrates be readily distinguished from all 
oilier salts 1 What nitrates are found in the native state? What is the composition of 
nitrate of potash 7 What is the common name of nitrate of pot-ash 7 What is the proceffl 
0/ preparing the nitre of commerce 7 



MTnATEfl. 277 

In the East Indies, this salt is formed spontaneously in the 
aoil, and is found in small crystals on its surface. It is there- 
fore obtained Avith great facility, nothing more being neces- 
sary than to lixiviate the earth and purify the nitre. 

Nitrate of potassa is a colorless salt, of a cool saline taste, 
which crystallizes in six-sided prisms. It contains no water 
of crystallization, but its crystals always contain more or less 
water mechanically retained in them. When heated, it un- 
dergoes the igneous fusion, and at a red heat is decomposed, 
first giving out oxygen, and afterwards both oxygen and ni- 
trogen, and if the heat be continued, there will remain only 
pure potassa. 

In chemistry, this salt is employed in the manufacture of 
nitric and sulphuric acids, and for the purpose of obtaining 
oxygen gas. In the arts, it is chiefly used in the manufac- 
ture of gunpowder and fire-works. 

Gunpoivder is composed by w^eight, of six parts nitre, on6 
part sulphur, and one of charcoal. These ingredients being 
first finely powdered separately, are then mixed into the form 
of a paste, with water, and beaten together with a w^ooden 
pestle, until they become very intimately incorporated. This 
paste is then granulated, by passing it through sieves, and 
carefully dried in the sun. 

Fulminating poivder is made by mixing in a mortar three 
parts of nitre finely powdered, two parts of carbonate of pot- 
ash, and one part of sulphur. The whole being thoroughly 
mixed by grinding, forms the powder in question. 

When a quantity of this mixture is placed on a shovel, and 
heated gradually, until the sulphur begins to inflame, it ex- 
plodes, giving a loud and stunning report, and leaving the 
ears hardly in a state to hear any thing more for hours, or if 
ihe quantity be considerable, even for days. Not more than 
15 or 20 grains of this powder should be exploded at once, 
unless in the open air. 

Nitrate of Ammonia. — The mode of preparing this salt, 
fvas described under the article nitrous oxide. This salt is 
composed of one proportion of nitric acid 54, and one propor- 
tion of ammonia 17=71. It also contains one proportion of 
Water=9. 



In what country is nitre formed spontaneously 1 When nitre is heated, what gases 
are expelled, and what substance remains in the fire 1 What are the uses of nitre 7 
What is the composition of gunpowder 1 How is fulminating powder prepared 1 Horp 
is this powder used 7 

24 



278 NITRATES. 

Nitrate of Silver — 164. 

1 p. Nitric Acid 54-fl p. Silver lia 

Lunar Caustic. 

When silver is thrown into nitric acid, the metal is dis- 
solved, with a copious disengagement of red fumes, which 
consist of the deutoxide of nitrogen, formerly described. 

The solution, if allowed to evaporate, will form large regu- 
lar crystals in the shape of flat rhombs. These, if the metal 
is unalloyed, are pure nitrate of silver. They contain no wa- 
ter of crystallization. They undergo the igneous fusion at a 
very moderate heat, and in this state, being cast into small 
cylindrical moulds, form the substance so well known, and 
so universally employed in surgery, and for other purposes, 
under the name of lunar caustic. 

A solution of this salt in water, being applied to animal or 
vegetable substances, stains them, after exposure to light, of 
a permanent black color. The skin or hair may be made 
black in this manner, and there is no doubt but persons have 
colored their faces and hands with this substance, as prepa- 
ratory to the commission of the worst of crimes. No washing, 
or any other means, will whiten the skin, once stained with 
this solution, until the scarf-skin itself wears ofl[^ or is removed, 
which requires several weeks. The solution itself is perfectly 
transparent, and in appearance cannot be distinguished from 
pure water. 

Indelible Ink is a solution of nitrate of silver in water, and 
is well known as the only substance in use, with which cot- 
ton and linen may be marked in a permanent manner. 

Nitrate of silver, in solution, is decomposed by a variety 
of substances, having a stronger attraction for oxygen than 
the silver has. By the action of such substances, the silver 
is revived, and appears in its metallic form. Thus, a stick of 
phosphorus placed in this solution, is soon covered with me- 
tallic silver ; and if the solution be heated to the temperature 
of boiling water, with a little charcoal in it, the metal will be 
reduced, and maybe obtained in the form of crystals. 

The composition of the nitrate of silver is seen at the head 
of this section. 

When silver is thrown into nitric acid, what gas escapes 7 What is the composition 
of nitrate of silver 7 What is the common name of nitrate of silver? What is lunar 
caustic? What effect does a solution of nitrate of silver have on the skin, or hair 7 
What is indelible ink 7 What sulietancce are mentioned, which decompose nitrate of 
filver'' 



CHLORA.TES. 279 

There are many other nitrates, but none of them are of 
sufficient use, or interest, to require a description in this 
book. 

CHLORATES. 

The chlorates resemble the nitrates in many of their cha- 
racters. These salts were formerly called oxymuriates. Most 
of them are decomposed at a red heat, with the evolution of 
pure oxygen gas, and are converted into metallic chlorides. 
The pupil may find some difficulty in pointing out the dis 
tiDCtion between the chlorates and chlorides. The chlorates 
are composed of chlorine united to oxygen, forming chloric 
acid, which acid, being combined with the metallic oxides, 
forms chlorates. The chlorides are composed of uncombined 
chlorine, either united to the metals themselves, or their 
oxides. Thus, chloride of lime is composed of lime, or oxide 
of calcium, and chlorine. But chloride of calcium is compo- 
sed of the two simple bodies, chlorine and the metal calcium, 
consequently contains no oxygen. 

When the chlorates are decomposed by heat, as above 
stated, and converted into chlorides, the change is produced 
by the expulsion of the oxygen which the compound contain- 
ed, and the subsequent union between the chlorine and the 
base of the alkali, or the metal itself Thus, when chlorate 
of potassa is heated, its oxygen escapes, while the chlorine 
remains, and combines with the base of the alkali, forming 
chloride of potassium. 

In producing the chlorates, it is not necessary that the 

chloric acid should first be formed, and then combined with 

the salifiable base, since the same result is produced by mere- 

I ly passing the chlorine through a solution of the alkali. This 

will be explained under the chlorate of potassa. 

The chlorates are all of them artificial compounds, none 
of them having been discovered in the native state. Most 
I of them yield their oxygen to combustibles with such facility 
' as to produce explosion. Thus, when chlorate of potash is 
! rubbed in a mortar with phosphorus, or struck in contact 
I with sulphur, violent detonations are produced. 



What were the chlorates formerly called 1 What is said of the decomposition of the 
chlorates by heat 1 What is the difference between the chlorates and the chlorides ? 
What are ths chemical changes by which the chlorates are converted into the chlorides 1 
j In producing the chlorates, is the chloric acid first formed, or is it only necessary to pass 
f Jie chlorine through the alkaline solution 1 Do any of the chlorates occur in nature 1 
; What is said of the facility with which the chlorates yield their oxygen to combustiblea 1 



280 CHLORATES. 

Chlorate of Potash — 124, 

1 p. Chloric Acid 76+1 p. Potash 48. 

Oxymuriate of Potash. 

The chlorate of potash is formed by passing chlorine gas 
through a solution of the pure caustic alkali in water. 

The pure potash is readily prepared in the following man 
ner. Make a solution of the carbonate of potash in its own 
weight of hot Avater, in an iron vessel, and add to this as 
much quicklime by weight as there was potash, and let the 
mixture boil for about ten minutes. Then strain the solution 
through a linen cloth, and it will be fit for use. 

The lime absorbs the carbonic acid from the potash, form- 
ing with it an insoluble compound, thus leaving the alkali in 
its pure, or caustic state. 

The caustic potash being placed in a proper vessel, the 
chlorine is passed into it as long as any of the gas is ab- 
sorbed. 

The apparatus for this purpose is represented at Fig. 64. 
Fig. 64. The solution is contained 

in the three necked bottle. 
The chlorine may be evol- 
ved by first introducing into 
the retort two ounces of 
finely powdered black oxide 
of manganese, and after eve- 
ry thing is arranged, as in 
the figure, pouring on this, through the safety tube, four 
ounces of muriatic acid, and then applying a gentle heat. 
When the solution is saturated, the gas will pass ofl!' by the 
bent tube into the open air. 

To obtain the salt, the solution is evaporated with a gentle 
heat, and on cooling, small shining crystals of chlorate of 
potash will be deposited. The first product only must be 
reserved for use, as the solution will afterwards form crys- 
tals of muriate instead of chlorate of potash. 

In the production of this salt, by the above process, the 
chloric acid is formed by the decomposition of the water, 
the oxygen of which unites with one portion of the chlorine 



What 13 the composition of chlorate of potash 1 How is caustic potash prepare^ 1 
What IS the use of the lime in preparing caustic potash 7 Explain the process by whA.b 
fhlorate of potash is formed. How is the chloric acid formed by this process 'i 




CHLORATES. 231 

to forai the acid, while the hydrogen thus disengaged, unites 
with another portion of the chlorine, forming muriatic acid. 
Hence the solution, as above intimated, contains both muriate 
and chlorate of potash. 

When chlorate of potash is heated, it gives off oxygen gas 
nearly pure, and chloride of potassium remains. 

If two grains of this salt are mixed with one grain of 
sulphur, and the mixture is struck, or pressed suddenly, a 
loud detonation is produced. When struck in contact with 
powdered charcoal, a similar effect results. If a grain of 
the chlorate and half a grain of phosphorus be rubbed to- 
gether in a mortar, very violent detonations wdll be the effect. 
In making this experiment, the hand should be covered with 
a glove, and the face protected by a mask, or averted, as the 
inflamed phosphorus is sometimes projected several feet by 
the explosion. 

If a little of this salt be mixed with tw^ice its weight of 
w^hite sugar, and on the mixture a few drops of strong sul- 
phuric acid be poured, a sudden and vehement inflammation 
will be produced. 

These phenomena are owing to the facility with w^hich the 
chlorate of potash parts with its oxygen to combustible sub 
stances. 

This salt forms the base of the red French matches, by 
which a light is instantly obtained. The chlorate being 
finely pulverized by itself, is then mixed wdth twice its 
weight of w^hite sugar, moistened so as to prevent explosion, 
and afterw^ards made into a paste with mucilage of gum ara- 
ble. A little of this paste is fixed on the ends of brimstone 
matches, so that when it is inflamed, first the sulphur ana 
then the w^ood is set on fire. These matches require only to 
be touched wdth a drop of sulphuric acid, when they instant- 
ly burst into flame. The acid, for convenience, is contained 
in a small vial, and is prevented from escaping by some fibres 
of asbestos. 

Attempts are said to have been made in France, on a large 
scale, to substitute the chlorate of potash for nitre in the 
manufacture of gunpowder. But it w^as found that the 
workmen could not mix the ingredients, under any circum- 



Whence comes the muriate of potash which the solution contains 7 Mention some of 
the experiments which may be made with this salt, and a combustible. How are the 
^ftd matches prepared from this salt 1 What is said of the attempts made to substitute 
Uie chlorate of pota!?h for nitre, in the preparation of gunpowder 7 

24* 



282 PHOSPHATES. 

Stances without the greatest danger, and that in many in 
stances explosions took place after the powder was prepared ; 
the attempt was therefore abandoned. Attempts have also 
been made to use mixtures of this salt for percussion priming, 
but it was found that the chlorine acted so readily on the 
iron, as soon to injure the gun, and it w^as therefore laid 
aside, for the fulminating mercury, which is now generally 
used for this purpose. 

PHOSPHATES. 

The phosphates of the metals are converted into phospu- 
rets by heat and charcoal. Some of the alkaline and earthy 
phosphurets undergo a partial decomposition by the same 
means, while others are not changed. A number of phos- 
phates are found in the native state, such as those of iron, 
lime, copper and lead. 

Phosphate of Soda — 60. 
1 p. Acid 28 + 1 p. Soda 32. 

This salt is prepared on a large scale in chemical manu- 
factories, by neutralizing wath carbonate of soda, the super- 
phosphate of lime, procured by the action of sulphuric acid 
on burned bones. The phosphate of lime which the solution 
contains, is separated by filtration, and the liquid containing 
the phosphate of soda is then evaporated until crystals of the 
salt are deposited. 

The phosphate of soda is com.posed of one proportion of 
the acid 28; one proportion of soda 32; and twelve propor- 
tions of water 108. It is employed in medicine, and in chem- 
istry as a re-agent. 

BORATES. 

The borates are few in number, and being most of them 
of no use, are little known. They are distinguished by 
imparting a green color to the flame of alcohol, when 
dissolved in it. Any borate, being first digested in sul- 
phuric acid, then evaporated to dryness, and the residue 



What are the phosphates which occur in the native state 1 ^^^lat is the eompositlon 
of phosphate of soda 7 How is the phosphate of soda prepared on a large scale ? What 
w the use of phosphate of soda ? How are the borates distinguished 1 



FLUATKS. 283 

boiled m alcohol produces this effect. Hence, this is thetesi 
for these salts. 

Biborate of Soda — 80. 

2p B. Acid 48+1 p. Soda 32. 

Borax. 

This is the only borate of any consequence, either in che- 
mistry, or the arts. It occurs native in certain lakes in Persia 
and Thibet, which are said to be supplied by springs. The 
edges and shallow parts of these lakes are covered with a 
crust of borax, which being removed, another deposition is 
formed. It is imported into Europe and America in its rough 
or impure state, under the name of Thvcal, and which being 
purified, forms the refined borax of commeice. 

This salt is capable of being crystallized, in six sided 
prisms, though more commonly seen in amorphous pieces. 

It is soluble in six times its w^eight of boiling water. When 
exposed to heat, it enters into the watery fusion, and at the 
same time, swells to several times its former bulk. When the 
water of crystallization is expelled, it passes silently into the 
igneous fusion, and forms a vitreous transparent globule, 
called glass of borax. Borax is used as a flux, by braziers, 
and mineralogists, and is employed in medicine, in cases of 
sore mouth. 

Besides the constituents of this salt placed at the head of 
this section, borax contains 8 atoms, or 72 parts of water of 
crystallization. 

FLUATES. 

The nature of the fluates, owing to the uncertainty which 
exists concerning the base of the fluoric acid, are little known. 
These salts may, however, be readily identified by first redu- 
cing them to powder, and pouring on sulphuric acid, when, 
with the aid of a gentle heat, fluoric acid will be disengaged, 
and may be recognized by its property of corroding glass. 

Several fluates are found in the native state, and it is from 
these only, or rather from one of them, the fluate of lime, 



What is the composition of the biborate of soda 7 What is the common name of this 
salt 7 Where is borax found 7 What is glass of borax? What are the uses of borax 1 
What proportion of water does borax contain ? How may the fluates be known 7 From 
what natural substance is the fluoric acid obtained 7 



284 CARBONATES. 

chat the fluoric acid is obtained. The topaz is a compound 
of fluoric acid, alumine, and silex. Its chemical name \s 
Auosilicate of alumina. 

Fluate of Lime — 38. 

1 p. F. Acid 10+1 p. Lime 28. 

Derbyshire Spar, 

This salt is found in its native state, in many parts of the 
world. It is often seen as an article of luxury, cut into the 
form of vases, candlesticks, or boxes, under the name of 
Derbyshire spar. Its colors are purple, green, red, blue, 
and white, often mixed in the same specimen, and forming 
-one of the most beautiful of mineral substances. This sub- 
stance crystallizes in a great variety of forms, the cube bein£^ 
the most common. 

Some varieties of this salt phosphoresce, when thrown upon 
hot iron, emitting light of various colors, as green, red, blue, 
&c. 

When fluate of lime is exposed to the united action of sul- 

f)huric acid and heat, it is decomposed, the fluoric acid being 
iberated in the form of gas, while a sulphate of lime is formed. 
By this method the fluoric acid is obtained, 

CARBONATES, 

Some of the carbonates exist in great abundance in the 
native state. The carbonate of lime forms entire mountains. 
These salts may generally be distinguished from all others by 
their effervescence, when exposed to the action of the stronger 
acids. This is owing to the escape of carbonic acid during 
the decomposition of the salt. Thus, when sulphuric acid is 
poured on carbonate of lime, the lime and acid combine, while 
the carbonic acid, being thus liberated, escapes through the 
solution, and occasions the eflfervescence. 

The carbonates, with the exception of those of potash, soda, 
and ammonia, are very sparingly soluble in water. The 
carbonate of lime is entirely insoluble in pure water, but is 
slightly soluble in water containing carbonic acid. 



What is the chemical name of topaz 1 Wh* < is the composition, and what the com 
bining number, of fluate of 1 ime 1 What is the common name of fluate of lime 1 How it 
the fluoric acid obtiiined 1 What carbonate lorms entire mountains 7 How may thu 
cajfbcnates be distinguished from all other salt«'? Wliat occasions the effervescence when 
tarbonate of lime is acted on by a strong acid 1 



CARBONATES. 1JS$ 

Many carbonates of the metals as well as of the earths are 
found native. The carbonates of lime, of soda, barytes, stron- 
tian, magnesia, manganese, of iron, copper, and lead, are all 
native salts. 

Carbonate of Potash — 70. 

1 p. C. Acid 22+1 p. Potash 48. 

Potash, Pearlash. 

The well known substance pearlash, is the potash of com- 
merce deprived of its impurities, and saturated with, carbonic 
acid. The potash of commerce is obtained by lixiviating the 
ashes of land plants, or common wood, and evaporating th^ 
solution to dryness. In this state it is of a dark reddish co- 
lor, and when recently prepared, is exceedingly caustic to 
the taste and touch. By age its caustic property is gradually 
lost, in consequence of the absorption of carbonic acid from 
the atmosphere. Potash is chiefly employed in making soft 
soap and glass. 

The bicarbonate of potash is prepared by transmitting a 
current of carbonic acid gas through a solution of the carbo- 
nate. This salt contains 44 parts of carbonic acid and 48 
parts of potash, making its equivalent 92. It also contains 9 
parts or one proportion of water of crystallization. This is 
far milder, both to the touch and taste, than the carbonate. At 
a red heat it parts with one proportion of its acid, and is re- 
duced to a carbonate. 

This salt is in common use under the name sal (gratis. It 
is employed for culinary purposes ; in many of the arts, and 
in medicine. 

The bicarbonate of potash maybe obtained in regular pris- 
matic crystals by evaporating its solution gradually. 

Carbonate of Soda — 54. 

1 p. C. Acid 22+1 p. Soda 32. 

Sod^a. 

The carbonate of soda is prepared byburnnig plants which 
grow in the sea, and lixiviating their ashes. The impure 



What carbonates are found native 1 What is the composition of carbonate of potash 1 
What is the common name of carbonate of potash? How is potash obtained I What 
we the uses of potash 7 How is the bicarbonate of potash prepared? What is ihe com 
imm r^ame of bicarbonate of potash 1 How is ths carbonate of soda prepared % 



*S86 CARBONATES 

soda of commerce is known under the name of barilla, and 
is obtained by burning certain sea plants expressly for the 
purpose. An inferior kind is called kelp, and is prepared 
with less care and from different plants. 

The carbonate of soda of commerce is prepared by dissol- 
ving barilla in water, filtering the solution, and then evapo- 
rating the water. If the evaporation is conducted slowly the 
salt shoots into regular crystals. By continued gentle heat 
these crystals part w4th their water, and are rendered anhy- 
drous without loss of carbonic acid. This salt dissolves in 
about its own w^eight of hot water. 

Carbonate of soda is composed of one proportion of the 
acid 22 ; one proportion of soda 32, and 10 proportions or 90 
parts of water. 

Hard soap is prepared entirely from soda. Bicarbonate oj 
soda is made by transmitting carbonic acid through a solu 
tion of the carbonate in water. It may also be prepared by 
placing vessels containing the carbonate in the vats of a dis- 
tillery or brewery, where the process of fermentation is car- 
ried on. By either process the carbonate is made to absorb an 
additional proportion of the acid, and is thus converted into 
the bicarbonate. 

This salt contains two proportions of the acid 44 ; one pro- 
portion of soda 32 and 9 parts of w^ater. 

The bicarbonate is in general use as a medicine, and forms 
the alkaline portion of soda powders. It also forms the bases 
of that agreeable beverage soda water. 

MURIATES. 

The muriates may be distinguished by the emission of mu 
riatic acid fumes when tested w4th strong sulphuric acid 
And also w^hen in solution, by forming a white insoluble 
chloride, when tested with nitrate of silver. The muriates^ 
when in a dry state, are chlorides. 

Muriate of Ammonia — 54. 

1 p. M. Acid 37+1 p. Ammonia 17. 

Sal Ammoniac. 

Sal ammoniac was formerly imported from the East, and 

particularly from Egypt ; but has for many years been ma- 

What is the name of the impure soda of commerce 1 What is kelp 7 What is the com- 
position of carbonate of soda 1 What kind of soap is made from soda 1 By what process 
is bicaroonate of soda made 1 How does the bicarbonate of soda differ from the carbonate 
of soda? What are the use* of bicarbonate of soda 1 What is the composition of muriati 
of amm.onla 1 



MURIATES. 



28r 



nufactured in large quantities, in several parts of Europe. 
Several processes are used at the different manufactories. 
The following is the method employed at a principal manu- 
factory in Paris. 

Two kilns are constructed of brick, in which are placed 
proper vessels for containing the materials employed. Into 
one of these vessels is placed a quantity of common salt, on 
which is poured sulphuric acid, and into the other are thrown 
animal matters, such as horns, bones, parings of hides, &c. 
On the application of heat there is extricated from one vessel, 
muriatic acid gas, and from the other, ammonia. These 
gases are conducted by flues into a chamber lined with lead, 
where they combine, and form solid muriate of ammonia, 
which incrusts the roof and sides of the room, and enters 
mto solution with a stratum of water on the floor. 

Muriate of ammonia, as seen above, is composed of mu- 
riatic acid and ammonia. Both these constituents exist in 
the state of a gas, but when combined they form the solid 
compound in question. 

The elements of ammonia, (nitrogen and hydrogen,) exist 
m all animal substances, and the muriatic acid is a constitu- 
ent of common salt. In the above process the ammonia is 
extricated by the heat, while the muriatic acid is evolved by 
the decomposition of the common salt. 

This mode of preparing sal ammoniac may be illustrated 
in the following manner, and affords a very instructive and 
satisfactory experiment. 

Fig. 65. Provide two flasks, each furnished with 

a tube, as represented at Fig. 65. Into one 
of these put a handful of common salt, 
and a little sulphuric acid, and into the 
other put equal parts of powdered quick 
lime and sal ammoniac, ground together. 
Then invert over the ends of the tubes a 
tall bell glass, or a tubulated receiver, as 
_ seen in the figure, and apply a gentle heat 
tt to the bottom of each flask. The two 
^^^ gases will be disengaged, and combining, 
^y^will form a white cloud within the receiver, 
^ ^ — ^ which will gradually condense and cover 
^-^ ^ its surface with solid sal ammoniac. If 

What is tne coramon name of muriate of ammonia ? W^hat is the process for making 
muriate of ammonia ? How may the process of making the muriate of ammonia ba 
^ustrated by the apparatus represented at Fig. 65 1 




ttYDROSULPHURETS. 

one of the g^ses be introduced into the receiver without the 
other, it will remain transparent and unseen until it meets 
the other, when a dense white cloud will instantly be formed. 

In this experiment the ammonia is set free, in consequence 
of the decomposition of the muriate by the quicklime, which 
combines Avith its muriatic acid. 

The article used in smelling bottles, and called volatile. 
salts, hartshorn, ^'c, is a carbonate of ammonia. 

Muriate of Barries — 115. 
2 p. Muriatic Acid 37+1 p. Barytes 78. 

This salt is formed by saturating muriatic acid with carbo- 
nate of barytes. For this purpose, either the native or arti- 
ficial carbonate may be employed. 

Muriate of barytes crystallizes in four sided tables, ano' 
contains nine parts, or one proportion of water. It is solu 
ble in about two and a half times its weight of water ; and 
is much employed as a re-agent in chemistry. 

HYDROSULPHURETS. 

Sulphuretted hydrogen is formed by the action of muriatic 
acid on sulphuret of antimony, or some other metallic sui- 
phuret. 

This gas is capable of forming salts Avith the alkalies, ot 
alkaline earths, when passed into their aqueous solutions. 
It thus performs the office of an acid, and the compounds so 
formed are called hydro sulphur ets. 

The hydrosulphurets are all of them easily decomposed, 
with the disengagement of sulphuretted hydrogen ; the fetid 
odor of which, seldom leaves the experimenter in any doubt 
concerning the character of the compound. 

Hydro sulphuret of Potash. 

The best method of making this salt, or of impregnating 
water wath any other gas, is by means of the apparatus re- 
presented by Fig. 66. 



What is the composition, and what the combining proportion, of muriate of barytes? 
How Is the muriate of barytes prepared! What are the hyfliosulpburets? How art 
<hc hydrosulphurets formed 1 



ORGANIC CHEMISTRY. 



28B 



Pig. 66. 



The solution of pure potash 
in water, is placed in the lower 
vessel, while the materials for 
extricating the sulphuretted hy- 
drogen are contained in the re- 
tort. The influx of the sulphu- 
retted hydrogen into the lower 
vessel, drives the fluid into the 
upper one, the juncture between 
the two being made close by 
grinding. Thus, the fluid press- 
ing on the gas, the absorption 
of the latter is greatly facilita- 
ted. In this manner soda water 
may be made, the tube in the 

_- -.upper vessel being convenient 

tor the introduction of an additional quantity of soda, when 
required, or for a similar purpose when experimenting on 
other substances. These vessels being made of glass, the 
changes in the height of the fluid, and consequently its de- 
gree of pressure on the gas, are made obvious. 

This salt forms large transparent crystals, in the shape of 
six-sided prisms. Its taste is bitter, and it is soluble in water 
and alcohol. 




PART III. 



ORGANIC CHEMISTRY. 

Organic chemistry comprehends the chemical history of 
all those different substances or elements, which form vege- 
table and animal bodies. 

In many respects this department of chemistry difl^ers 
very materially from that of the mineral kingdom. The ana- 
lysis of inorganic bodies show, that each substance which 
differs materially from another substance, contains some 
principle peculiar to itself, or that the difference arises from 
the multiplied proportion of some one constituent, while the 
other remains the same. Numerous instances of both these 



Explain Fig. 66, an J deejcribe in what manner the water presses on a gas generated in 
fee retort, and forced into the lower vessel. What does the third part of this volmna 
treat of "J What does organic chemistry comprehend 1 In what reapecf doesorgtrwi 
chemistry difffer from mineral ch*»raietry1 

25 



290 ORGANIC CttEMlSTRY. 

cases will be found, on referring to the composition of variant 
substances, and to such compounds as are formed by the un'on 
of different, but definite proportions of the some elements. 
Thus, sulphur united with oxygen, and carbon united to the 
same element, form two compounds differing from each other 
in every respect, with the exception that they both combine 
with salifiable bases and form salts. And mercury, with one 
proportion of chlorine, forms a compound, which may be taken 
in large doses, and is in general use, as a medicine, while with 
another proportion of the same element, it becomes one of 
the most corrosive poisons known. 

On the contrary, the elements of organized bodies are 
comparatively few in number, and although the different 
products, of which there is a great variety, must be com- 
posed of different proportions of these few elements, yet the 
resulting compounds of the same elements never present 
qualities differing widely from each other, like those of the 
mineral kingdom. 

There is another wide difference between organic and in- 
organic chemistry. The latter presents us only with com- 
pounds formed in consequence of affinity, or the attraction of 
the heterogeneous particles of matter for each other. But 
organic substances are formed by the action of peculiar or- 
gans, each organ being endowed wuth the power of produ- 
cing different results from similar elements. 

Thus, the several organs of the same tree produce wood, 
bark, flowers, fruit, gum, honey, &c., from the same elf»- 
mentg : while the organs of secretion, and growth, in ani- 
mals, produce bone, marrow, flesh, bile, fat, hair, nails, &c., 
from the same food. 

In general the chemist finds little difficulty in decompo- 
sing, and afterwards imitating the products of the mineral 
kingdom, by again joining the same elements to each other. 

But although he can decompose the products of organic 
action, and find the proportions of their elements, he never 
has been able to recompose or imitate these compounds. 
Thus, sugar and gum, are found to be composed of hydro 



What is said of the number of elements in organized bodies ? Wliat is the differenca 
m the mode in which inorganic and organic substances are formed 1 ^\^lat substances 
docs the different organs of a tree form, from the same elements 7 What are the different 
fubsiances mentioned, which the several organs of an animal produce from the earn? 
foodl What \w said of the power of the chemists to imitate inorganic and organic sub- 
stances t 



VEGETABLE CHEMISTRY. 231 

gen, ox^'gen, and carbon, and the exact proportions of these 
elements which they contain, are known ; but no chemist has 
yet found the means of combining these elements, so as again 
to form sugar and gum. 

Organic substances differ also from inorganic, in their ten- 
dency to decomposition. Thus, all animal and vegetable bo- 
dies, without exception, when exposed to the agencies of an 
and moisture, undergo spontaneous changes, their elements 
entering into new combinations, and forming new compounds 
to the entire destruction of the old ones. The compounds of 
the mineral kingdom, on the contrary, are generally perma- 
nent, many of them having probably not suffered the least 
change since their creation. 

The changes which result from the decomposition of ani- 
mal and vegetable substances, are often exceedingly compli- 
cated, and particularly when this is produced by heat, and in 
a close vessel. A compound, consisting of carbon, hydrogen, 
and oxygen, when thus treated, will produce water, carbonic 
acid, carbonic oxide, and carburetted hydrogen, and if the 
substance contains nitrogen, in addition to these, there will 
also be formed ammonia, and cyanogen. 

VEGETABLE CHEMISTRY. 

Before proceeding to describe particular substances, or the 
means by which the composition of vegetable products are as- 
certained, and to show the elements of which they are com- 
posed, we shall give a short account of the process of vegeta- 
tion, and point out the chemical changes v/hich take place 
during the growth of plants. 

We have already stated, that the elements of which vegeta- 
bles are composed are few in number, and that the great 
variety which we observe in plants, and their different parts, 
must therefore arise from the different proportions in which 
these few elements unite. 

The constituents of vegetables are carbon, hydrogen, an^i 
oxygen, to which is occasionally added small proportions c 
nitrogen. The nitrogen, however, occurs only in such plants 
as emit the animal odor during their decomposition, as cab- 
bage, and some of the mushrooms. 



What is the difference between inorganic and organic bodies with respect to the tenden- 
cy to decomposition 7 What is said with respect to the complicated changes which or- 
ganic bodies undergo, by decomposition? What are the elements or constituents or 
which all vegetables are composed ? How is the great variety under which veget«U)lfii 
appear accounted for, when their elements are so few in number I 



2\)2 



VEGETATION. 



Notwithstanding- the great variety which we observe in the 
texture, color, taste, smell, hardness, and other properties of 
different plants, as well as their several parts, such as flowers, 
seeds, and fruits, it is certain that their compositions differ 
only in respect to different proportions of these elements. 

The essential organs of plants, are the root, the stem, the 
leaves, the flowers, and the seeds. TKe root serves to attach 
the plant to the soil, and is one of its organs of nutriment. 

The ste7n, which is usually erect, serves to elevate the 
leaves, the flower, and the fruit, from the ground, by which 
they are exposed to air and light. The leaves are the respi- 
ratory organs of the plant, and the flower performs the im- 
portant office of giving rise and nourishment to the seeds, by 
which the plant is reproduced. 

When a seed is exposed in a situation which favors its 
growth, it soon undergoes a change. It swells, grows soft, 
bursts its membrane, or shell, and at the same time, from be- 
ing insipid and farinaceous, it becomes sw^eet and mucilagin- 
ous, thus becoming fit nourishment for the new plant. The 
stem and leaves are soon after elevated above the earth, in 
search of air, warmth, and light, while the root sinks into the 
ground in search of moisture and nourishment. 

The seed, however various in form, consists essentially of 
the cotyledon, the plumula, and the radicle. The cotyledon 
contains the matter necessary for the early nourishment of 
the young plant. Sometimes this is single, sometimes double, 
and sometimes it is divided into lobes. The plumula is en- 
veloped within the cotyledon, and is the part which produces 
the stem and leaves. The radicle shoots downwards, and 
becomes the root. 

The garden bean, having been 
a few days in the ground, shows 
all these parts in perfection, and 
is represented by Fig. 67. The 

^P! ^ cotyledons form the bulk of the 

"^' seed, and are marked a a. The 

plumula b, and the radicle c, are 
v^ represented as beginning to shoot, 
c while d d mark the membrane by 

which the whole has been enclosed. 




What are the essential organs of plants 7 What purpose do each of these organs serve 1 
When a seed is placed in circumstances favorable to its growth, what changes does it u» 
dergo 1 What is said of the stem and roots ? Of what does 3 seat' -issentia.'ly 'X)naiSt ) 
yy\mi IS the cotyledon 7 



VEGETATION. 293 

The circumstances necessary for healiliy geiTninatiorx aro, 
a temperature above the freezing point, and below 100 de- 
grees ; moisture in a certain proportion, depending on the 
kind of seed ; and a proper access of air. 

The joint operation of these several agents seem absolutely 
requisite ; for seeds exposed to the action of air and moisture, 
at a temperature below 32°, will not grow, though they may 
not be absolutely destroyed by the frost. Nor w^ill seeds ve 
getate without the contact of some air, though both heat and 
moisture be present. This is shown by burying seeds deep 
in the ground, where they are known to lie in a torpid state 
for years, and in some instances, it is supposed, even for cen- 
turies. Thus, when alluvial soils are exposed to the sun, 
though taken from many feet below the surface, they afford 
grass from the seeds they already contain, and which had 
before remained torpid an unknown length of time, for want 
of the germinating power of oxygen. 

This curious fact is confirmed by the experiment of Mr. 
Ray, who found that seeds exposed to heat and moisture, but 
confined in the exhausted receiver of an air pump, showed 
no signs of germination. 

Other experiments have proved that seeds will not grow 
under any circumstances, without the presence of oxygen. 
Healthy seeds, supplied with abundance of heat and moisture, 
but confined to an atmosphere of nitrogen, carbonic acid, or 
hydrogen, showed no signs of germination. 

It appears, however, that only a very small quantity of 
oxygen is required for this purpose, for Mr. Ray found that 
when the receiver of his air pump was not completely ex- 
hausted, the seeds would sprout. In this respect several ex- 
perimenters have been deceived, and in consequence of not 
producing a complete vacuum, have concluded that air was 
not necessary for the process of germination. 

It being thus certain that seeds will not germinate without 
the aid of oxygen, it hardly need to be stated that the future 
growth of the plant must require the presence of the same 
principle. 

The immediate source from which plants draw their nou- 



What is the plumula 1 What is the radicle 1 What are the circumstances necessary 
to healthy germination 7 Will seeds grow, when exposed to air and moisture, under 32 
degrees'? How is it shown that seeds will not vegetate without air 7 What was Mt, 
Ray's experiment on the gro^vth of ssecb 1 What g»s is absolutely nece^ary tc the 
grcwth of seeds 1 

2S* 



294 VEOETATION. 

rishment, has been a matter of doubt and controversy. It k 
certain, however, that they will not ^row without the pre- 
sence of heat, air, and moisture. It also seems necessary for 
their vigorous growth, that their roots should be placed in 
the earth, but whether this is requisite for their nourishment, 
or whether the ground serves merely to give them support, 
was a question long in dispute. 

Van Helmont planted a willow which weighed 5 pounds, m 
a pot containing 200 pounds of earth. This he watered lor 
the space of five years, and, at the end of that time, the tree 
was found to weigh 169t pounds, while the earth in which it 
had stood, being dried as at first, was found to have lost only 
two ounces. Here, then, was an increase of 164 pounds 
weight, and yet the food of the plant had been water only. 
This experiment was supposed to settle all controversy, and 
to decide that the sole food of plants was water. But Mr. 
Boyle afterwards showed, that the water with which the tree 
was moistened, contained earth, from which the willow de- 
rived at least a part of its nourishment. 

After a great variety of curious, and many elaborate ex- 
periments, on this subject, it has been ascertained, that plants 
will germinate in pure water, and that the young plant, for a 
time, will grow with no other aliment; but that it finally grows 
sickly, and does not come to maturity and produce seed, with- 
out other nourishment. 

A proof that plants do not thrive on water alone, is drawn 
from the well known fact, that soils become ierile by a long 
succession of crops, but are again made productive by the 
addition of new ingredients. 

Nor does it appear that the simple earths, or clay, without 
some additional ingredients, are sufficient to support the 
growth of vegetables. On making an experiment, by plant- 
ing seeds in pure silica, alumina, or magnesia, moistened 
with pure water, and exposed to proper degrees of heat, it 
was found that, although germination was effected, the young 
plants did not grow, until supplied with water, which con- 
tained vegetable or animal remains in solution. 



What are the agents necessary for the vigorous gi'owth of a plant 1 What was the 
experiment of Van Hehnont, and what was it supjiosed to decide 1 How did Mr. Bcjie 
show that the willow did not live on water alone ? What has been ascertained with res- 
pect to the growth of plants In pure water 7 What common fact, concerning soVj*, 
shows lliat plants will not thrive on water alone "l What ia said of the growth of yeg*- 
unbles in the pure earths ? 



VEGETATION. 295 

It is for this reason, that earth, taken from a depth below 
the surface, never forms a productive soil. The soils best 
adapted to the growth of plants, always contain a proportion 
of vegetable mould, that is, the remains of decayed vegeta- 
bles. This mould contains a quantity of matter which is so- 
luble in water, and it is probable that the fertility of a soil 
depends in a degree on the quantity of soluble matter it con- 
tains, and that in this manner the aliment of plants is prepared 
for absorption by the roots. 

The sap which is prepared from the fluid absorbed by the 
joots, is constantly ascending up the vessels of the plant du- 
ring its gro\^'th, until it arrives at the leaves. Here it under- 
goes a considerable change, the w^atery parts being thrown 
off by the perspiration of the leaves, while that w^hich re- 
mains is converted into a peculiar juice, called the true so.p, 
which, like the blood of animals, is afterwards employed in 
forming the various substances found in plants. 

The leaves of plants are not only their perspiratory organs, 
but they also serve the purpose of respiration, that is, they 
alternately absorb carbonic acid and emit oxygen at their 
surfaces. 

Plants constantly throw^ off moisture from their surfaces 
by perspiration, but the quantity is much larger during the 
day than during the night. Dr. Hales found that a cabbage 
transmitted daily a quantity of water nearly equal to half its 
weight. The office of transpiration is performed entirely by 
the under side of the leaf, and may be almost entirel}^ stoppea 
by spreading varnish on that surface. 

The fact that plants absorb carbonic acid was first observed 
by Dr. Priestley. Having suffered a sprig of mint to vegetate 
for ten da3^s in a quantity of this gas, which would instantly 
extinguish a candle, he found, at the end of that time, that 
the candle was not extinguished by it as before, but that the. 
flame continued for a while. Subsequent experiments have 
shown, that pure carbonic acid stops the growth of plants, 



Why does not the earth, taken from a considerable depth below the surface, form 
a productive soil? On what does the fertility of a soil appear to depend? Wliat 
changes does the sap undergo in the leaves? What is the true sap, and what its 
use ? What office do the leaves perform besides that of perspiration ? What propor- 
tion of water did Dr. HaLi-s find a cabbage to transmit 7 What part of the leaf throws 
oO moisture 1 What wu Dr. Priestley 's experiment with a sprig )( mint and carbonic 



296 VEGETATION. 

out that a small quantity is absolutely necessary to ncdltnx'ui 
vegetation. 

In Dr. Priestley's experiment, the sprig of mint could nut 
have qualified the air in which it was confined, for the sup- 
port of combustion, merely by the absorption of the carbonic 
acid. It must be inferred, therefore, from this experiment, 
that the plant not only absorbed carbonic acid, but that it gave 
out oxygen, or that it converted the carbonic acid into oxygen 
gas, and this inference has been confirmed by experiment. 

Plants, while growing in the light, absorb carbonic acid 
from the atmosphere, w^hich they decompose ; the oxygen, 
of which this acid is in part composed, being emitted, while 
the carbon is retained by the plant. 

If a growing plant, as a sprig of mint, be exposed to the 
sun, in a glass vessel filled Avith water, it constantly emits 
from its leaves small bubbles of air, which on examination 
are found to be oxygen gas. Now water, under ordinary 
circumstances, always contains a quantity of atmospheric air, 
and the atmosphere always contains a proportion of carbonic 
acid, and hence it may be inferred, that the water furnishes 
the air which the plant decomposes in this experiment ; that 
this is the case, is proved directly by making the experiment 
with water, deprived of its air by the air pump, or by boil- 
ing, when not a particle of oxygen is obtained. 

That it is the carbonic acid which the plant decomposes^ 
and from which the oxygen is derived, is proved by two facts. 
The first is, that vegetables are found not to emit oxygen, 
unless carbonic acid be present. The other is, that if the plant 
be confined in a mixture of carbonic acid and oxygen, the 
quantities of which are known, the proportion of oxygen will 
be increased, while that of the acid will be diminished. 

From these facts we arrive at the wonderful conclusion, 
that plants absorb carbonic acid from the atmosphere, and 
that they retain the carbon for their own nourishment, but 
return the oxygen to purify the air. And from all that is 
known, it is most probable that a great proportion, if not all 



In Dr. Priestley's experiment, what change did the mint produce on the carbonic acid 3 
When a plant is exposed to the sun in a vessel of water, whence comes the carbonic 
acid which it decomposes 7 What two facts prove that plants emit oxygen in conso 
quence of the decomposition of carbonic acid 7 When plants decompose carbonic acid, 
what becomes of the carbon 1 From what source is it probable that plants derive mofii 
of their carbon 1 



VEGETATION. 2^7 

the carLon which wood contains is derived from the atmos- 
phere in this manner. 

On the contrary, during the night, or Avhen the light of the 
smi is withdrawal, plants absorb oxygen, and form with it car- 
bonic acid, a part of which they emit, and a part is retained. 

It appears from experiment, that vegetables not only cease 
to thrive, but that they actually die, if deprived of this night- 
ly inspiration of oxygen. Thus, if a plant be confined du- 
ring the day in a portion of carbonic acid, it decomposes a 
part of this gas, which is replaced by the emission of an 
equal volume of oxygen. But at night a part of this oxygen 
is absorbed and converted into carbonic acid, which is again 
emitted. Thus, ultimately, the plant decomposes all the car- 
bonic acid, because it emits more oxygen during the day than 
it absorbs during the night. But if the oxygen w^hich is 
formed during the day is withdrawn at evening, that is, if the 
plant has a new supply of pure carbonic acid every day, it 
soon droops, and dies for the w^ant of its oxyg^n. 

The leaves of plants absorb water, as well as carbonic acid 
and oxygen. The great effect which the dew of night, or 
sprinkling with water, has on a drooping flower, is a proof 
that the leaves imbibe moisture. 

Experiments also prove, that detached leaves often live 
for weeks when swimming on the water, and that a plant 
which is dying for want of moisture at the root, will revive 
and grow, when a branch with its leaves is placed in a ves- 
sel of water. 

It is most probable, therefore, that during dry seasons, and 
w^hen there is a defect of moisture at the root, that the plant 
is in part sustained by the absorption of water from the air 
and particularly from the dew as it falls at night. 

In addition to heat, moisture, oxygen, and carbonic acid, 
healthy vegetation requires a certain quantity of light. It is 
well known that plants which grow in the dark are always 
nearly colourless, and that they appear weak and unhealthy. 
The disposition of plants to enjoy the light '^s expressed by 
.neir inclination towards it, when it is stronger in one direc- 
tion than in another. 



When do plants absorb oxygen from the amosphere 1 How is it shown that plants 
droop and die, when deprived of oxygen 1 How is it shown that the leaves of plants ab- 
sorb water 7 What agent does healthy vegetation require in addition to heat, oxygen, 
water, and carbonic acid'? How do plants show their disposition to enjoy the light ? 



298 VEGETATION. 

Thus, bean, or potato vines growing" in a dark cellar, v/ill 
always run towards the light, and if possible, will creep out 
into the open air. And flowers, growing in pots placed near 
a window, will always lean towards the light, so that to keep 
them in a vertical position the pots must often be turned. In 
thick forests, the trees grow tall for the same reason; they 
stretch upwards to enjoy the light and heat of the sun. 

Plants which grow in the dark contain more water, and 
Jess carbon, than those which grow in the sun. A plant which 
grew in the dark, on analysis of one of its branches, was 
found to contain only one ninetieth part of carbon ; but on 
allowing the same plant to stand for thirty days in the sun, it 
was found to contain one twenty-fourth part of carbon. 

This is readily accounted for, by the fact, that plants grow- 
ing in the dark, emit no oxygen, but give out carbonic acid, 
and hence the defect of carbonaceous matter which they con- 
tain. This also accounts for the circumstance, that when a 
healthy plant is placed in the dark, it not only ceases to form 
carbon, but actually loses a part of that which it before con 
tained, by the constant emission of carbonic acid. 

Recapitulation. 

1. Vegetable substances are chiefly composed of carbon, 
hydrogen, and oxygen, but sometimes contain portions ofnitro- 
gen. 

2. During the process of germination, the farinaceous sub- 
stance of the seed, become sweet, and affords nourishment to 
the young plant. 

3. Healthy germination does not proceed without the com 
Lined presence of heat, water, and oxygen. 

4. Seeds will not germinate in a vacuum, or in any gas 
which does not contain oxygen, though heat and moisture be 
l,re55ent. 

^^ Plants receive nourishment from the air, as well as from 
the earth. 

6. Plants nourished by pure water, and having access to 
the air, grow for a time, but do not produce seeds. 

7. The nourishment which plants receive by the roots, is 
probably in a state of solution in w^ater. 



Why do the trees in thick forests grow tall 1 What is the difference in composition be 
tween ilants growing in the dark, and in the light 7 How is the small quantity of carboa 
conta.neri in plants growing in the dark accounted for 1 The student should be able «? 
answei al] the questions involved in this recapitulatica 



vi^GtrAtiLE Acius. 299 

8. The sap undergoes a chaii.je in the leaves, where it 
parts with a portion of water, and is thus fitted to form the 
various substances found in vegetables. 

9. In the day time, plants absorb carbonic acid, retain the 
carbon, and emit the oxygen. 

10. In the night they absorb oxygen, and give out carbonic 
acid. 

11. Plants do not live unless they are permitted to absorb 
oxygen during the night ; nor will they live unless they ab- 
sorb a portion of carbonic acid during the day. 

12. Vegetation will continue for some time in either car^ 
bonic acid, or oxygen gas ; because when confined in carbo^ 
flic acid, plants emit a quantity of oxygen during the da7/, 
which they absorb at night ; and when confined in oxygen^ 
f hey give out a quantity of carbonic acid at nighty which again 
serves them during the day. 

13. Healthy vegetation absolutely requires the agency of 
light. 

14. Plants which grow in the dark, are white. They show 
their propensity to enjoy the light, by leaning, or creeping to- 
wards it. 

15. Plants, growing in the dark, do not absorb, and de- 
compose, but emit carbonic acid, and hence they contain a 
deficiency of carbon. 

VEGETABLE ACIDS. 

The vegetable acids are generally less liable to spontane- 
ous decomposition than other vegetable products. They 
form salts when combined with the salifiable bases. Most 
oi them are decomposed by hot nitric acid, being converted 
into carbonic acid and water. All of them suffer decompo- 
sition when exposed to a red heat. These acids are nume- 
rous, but a large proportion of them are of little consequence, 
md therefore we shall describe only the most useful. 

Acetic Acid — 50. 

4 p. Carbon 24. 3 p. Oxygen 24. 2 p. Hydrogen 2. 

Vinegar. 

The acetic acid, or vinegar, exists ready formed in the sap 

WTiat is said of tne tendency of vegetable acids to decomposition 7 How may the vcgc- 
wble acids be decomposed 7 \Miat is the composition of acetic acid 1 What is the corU' 
dwn ':ame of acetic acid 1 



300 VEGETABLE AClDiS. 

of some plants, either in a free state, or combined with liirtt^ 
or potash. It may be formed artificially either by the ace- 
tous fermentation, or by the destructive distillation of wood. 

In the first case, it is made by exposing wine, cider, beer, 
or any other liquid capable of passing through the acetic fer- 
mentation, to the action of the air. This last condition is ab- 
solutely requisite, for no liquid will form vinegar if prevented 
from the access of air, that is, from the presence of oxygen. 
The liquid must also be exposed to certain degrees of tem- 
perature, for the acetic fermentation does not proceed, when 
the thermometer is at 32 degrees, and but very slowly when 
it is near this point. 

In this process, little or no gas is evolved, but on the con- 
trary the oxygen of the atmosphere is absorbed, so that the 
liquid undergoes a slow oxidation. 

The vinegar obtained by the distillation of wood is called 
fyroligneons acid, that is, the acid of burned wood. When 
first made, it is very impure, and of a dark colour, holding 
in solution carbon, soot, tar, and volatile oil, which gives it 
a strong smell of smoke. It is purified by a second distilla- 
tion, and is largely employed for manufacturing purposes,' 
and particularly in the preparation of white lead. 

The acetic acid is distinguished from all other acids by its 
peculiar flavor, odor, and volatility. Its salts are called 
acetates. These salts are all of them decomposed at a rec 
heat, or by the action of sulphuric acid. 

Acetate of Lead — 172. 

1 p. A. Acid 50+1 p. Oxide Lead 112. 

Sugar of Lead, 

This salt is prepared by dissolving either litharge, or white 
lead, in distilled vinegar. The solution is sweet to the taste 
and hence its common name. It occurs in small shining 
crystals, which contain 27 parts, or 3 atoms of water. 
This salt is partially decomposed when abandoned to the ac- 



Isvinegarever found ready formed in plants? How may this acid be formed by art t 
What liquids form this acid by fermentation? What conditions are necessary to the pro- 
duction of vinegar by fermentation 7 What gas is absorbed from the air by the forming 
vinegar 1 What is the vinegar from distilled wood called ? How is the acetic acid dis- 
tinguished from all other acids 7 What is the composition of acetate of lead "^ Wlial 
is the common name for acetate of lead ? How is this salt prepcirea 1 In what manner 
!i mi? salt decomposed when exposed to the air, and what new salt isformod i 



VEGETABLE ACIDS. 301 

tion of the atmosphere. It parts with its water of crystalli- 
zation, and absorbs carbonic acid from the atmosphere, thus 
being changed into a carbonate, or into white lead. We 
have stated in another place, that in the manufacture of white 
lead, the same change is effected ; the lead being first dis- 
solved by the acetic acid, and afterwards changed into a car- 
bonate by the action of the atmosphere. 

The acetate of lead is largely employed in the process of 
colouring, and as a sedative and astringent in surgery. 

Acetate of Copper — 130. 

1 p. Acetic Acid 50+1 p. Oxide of Copper 80. 

Verdigris. 

This salt may be prepared by exposing metallic copper to 
the vapor of vinegar. The process appears to consist in the 
absorption of oxygen from the atmosphere by the metal, after 
which it is. dissolved in the acetic acid. 

Verdigris is manufactured largely in the south of France, 
by placing plates of copper between the refuse of grapes af- - 
ter the juice is pressed out, for the making of wine. The flu- 
ids which the grapes still contain, pass through the acetic 
fermentation, by exposure to the atmosphere, and after seve- 
ral weeks, the plates acquire a coat of the acetate, which 
being scraped off, they are again exposed to the same pro- 
cess. The acetate is afterwards purified by solution, and 
crvstallization. 

Oxalic Acid — 36. 

2 p. Carbon 12+3 p. Oxygen 24. 

Acid of Sorrel. 

The oxalic acid exists ready formed in several plants, and 
particularly in the oxalis acetosella, or wood sorrel, and also in 
common sorrel. It is readily prepared artificially, by digest- 
mg white sugar in Rve or six times its weight of nitric acid, 
and evaporating the solution to the consistence of syrup. On 
cooling, crystals of oxalic acid will be deposited; but they 
should be purified by solution in water, and again crystallized 
by evaporation. 



WTiat are the uses of acetate of iead 7 What is the composition fo acetate of copper 1 
VHiat is the common name of this salt 7 By what chemical process is this salt formed 7 
How is verdigris made in the large way? What i&the oxalic acid compfisedof? In what 
plants is this acid ready formed I 

26 



302 VEGETABLE ACIDS. 

Oxalic acid crystallizes in slender, flat prisms, which have 
an exceedingly sour taste, and which in solution combine with 
the salifiable bases, and form a class of salts called oxalates. 
These crystals contain half their weight of water of crystalli- 
zation. 

This acid is easily distinguished from all others, by the 
form of its crystals, and by its solution giving with lime water 
a white precipitate, which is not dissolved by adding in ex- 
cess of the same acid. Oxalic acid is one of the most prompt 
and fatal poisons knowm, when taken in large doses. Fatal 
accidents have many times happened, in consequence of mis- 
taking this acid for Epsom salts. 

This acid is employed by calico printers, for the purpose 
of discharging certain colors. It is also used in families, 
for taking out spots of iron mould, and other stains. 

The oxylates are none of them of much importance. The 
oxalates of potash, like the acid itself, is sold under the name 
of essential salt of lemons, for removing stains from linen. 

Tartaric Acid. 

4 p. Carbon 24+5 p. Oxygen 40+2 p. Hydrogen 2. 

Tartaric Acid — 66. 

Cream of tartar is the purified lees, or deposits of wine 
casks. From cream of tartar the tartaric acid is produced, 
by mixing the former with chalk in fine powder, and throwing 
the mixture into boiling water, by which the cream of tartar, 
which is a tartrate of potash, is decomposed, and a tartrate of 
lime is formed. The tartrate of lime is then washed, and de- 
composed by dilute sulphuric acid, which, combining w^ith the 
lime, sets the tartaric acid at liberty, where it remains in so- 
lution. This solution being evaporated, the tartaric acid is 
obtained in white crystals. 

This acid is employed by calico printers, to discharge false 
prints, and by tallow chandlers to whiten their goods. It is 
also used, when dissolved in a large quantity of water, as a 
coolinof beverao-e in the hot season. When mixed with car- 



How is this acid formed by an ? What are the salts called, which the salifiable basea 
form with oxalic acid 7 H(. w is this acid distinguished from others? What is said of its 
poisonous effects 1 Wliat are the uses of oxalic acid? What is the tartaric acid composed 
of? What is the substance from which tartaric acid is obtained ? By what process ia 
this acid obtained? What are the uses of tartaric acid ? What occasions the efferfefr 
cence of soda powlers 1 



VKGtTABLE ACIDS 303 

bonate of soda 'ii solution, it forms the efferyescmg draiigni 
called soda powder, of which large quantities are prepared 
and sold during the summer season. 

The effervescence, the only property which makes this 

drink agreeable, is occasioned by the union of the tartaric 

acid with the soda, in consequence of which the carbonic 

acid is liberated, and in escaping through the water, causes 

che effervescence. 

[ This acid is remarkable for its power of combining wJth 

I two bases at the same time, and forming double salts. The 

I most important of these salts is well known under the name 

of tartar emetic. 

Tartrate of Antimony and Potash — 354. 

2 p. Tartaric Acid 132+2 p. Protoxide of Antimony 156. 

1 p. Potash 48+2 p. Water 18. 

Tartar Emetic, 

This compound, so singular from the number of constitu- 
! ents it contains, is made by boiling the oxide of antimony 
called crocus metallorum, with tartrate of potash, or cream of 
. tartar. 

[ This salt crystallizes in transparent prisms, which after- 
i wards grow white and opaque by exposure to the air. It is 
I soluble in about fifteen parts of cold, and three parts of hot 
\ water. 

\ When dissolved in water, the solution gradually undergoes 
■ spontaneous decomposition, and becomes inert as a medicine. 
This may be prevented by the addition of about one third part 
alcohol to the aqueous solution. This salt is also decompo- 
sed by many re-agents, as by all the stronger acids, and seve- 
ral of the alkalies and alkaline earths, and even by vegeta- 
I ble substances. Infusion of nutgalls causes with it a whitish 
h precipitate, which is considered a compound of tannin and 
oxide of antimony. This compound is inert, and hence the 
1 decoction of chincona bark, as it contains tannin, has been 
I given as an antidote to an over dose of tartar emetic. 



Wliat is the chemical name of tartar emetic'? What is the composition of tartar 
[emetic] How is lanar emetic prepared 1 WTiat is said of the decomposition of the 
i aqueous solution of tartar emetic 1 How may this decomposition be prevented 1 Ex- 
I plain the principle on which chincona, or Peruvian bark, has been given as an antidote 
! to tana: emetic 



304 ANALYSIS OF PLANTS. 

Citric Acid — 58. 
4 p. Carbon 24+4 p. Oxygen 32+2 p. Hydrogen 2. 

Salt of Lemons. 

This acid is obtained from the juice of lemons, by the same 
process as that described for tartaric acid. Finely powdered 
chalk is added to the juice, as long as any effervescence en- 
sues. The citrate of lime thus formed, is insoluble in water, 
and sinks to the bottom of the vessel. This being washed, 
is digested in dilute sulphuric acid, by which an insoluble 
sulphate of lime is formed, while the citric acid, being thus 
set at liberty, remains in the solution, and on evaporation is 
obtained in crystals. 

These crystals are large, transparent, and beautiful. They 
undergo no change by exposure to the air, are exceedingly 
sour to the taste, but when dissolved in a large proportion of 
water, make an agreeable drink, in consequence of retaining 
the flavor of the lemon. 

This acid forms salts with the salifiable bases, but none of 
them are of importance. There is a variety of other vegeta- 
ble acids, most of which are of no importance in any respect. 
Some of these have been analyzed, while the composition ol 
others are unknown. We may, however, conclude, by ana- 
logy, that they are all composed of oxygen, carbon, and hy- 
drogen, in different proportions. 

Composition and Analysis of Vegetable Substances. 
When vegetable substances are submitted to destructive 
distillation, the carbon, oxygen, and hydrogen, of which they 
are composed, enter into new combinations, and there is 
obtained a variety of products, which differ from each other, 
according to the nature of the vegetables, and the mode of 
distillation. In general, these products are loater, pyroligne- 
ous acid, empi/reumatic or burnt oil, carbonic acid, and car- 
buretted hydrogen. If the vegetable contains nitrogen, a 
quantity of ammonia will be formed, and in either case, there 
will remain in the retort, a quantity of charcoal, with a small 
portion of earthy and saline matter. 



What is citric acid composed of 7 What is the common name of this acid 7 How is 
citric acid obtained 1 What is the use of citric acid 7 What are the new products intc 
which vegetables are resolved, by destructive distillation 7 How may these new arraj)|r« 
Hitn'* c f vegetables be accounted for 7 



ANALYSIS OF PLANTS. 305 

These several products are all composed of the same ulti- 
jiaie principles, but are newly arranged and combined in 
different proportions. The new arrangements may readily 
be accounted for, from the circumstance, that the several 
elements, being in contact with each other in the retort, are 
it full liberty to exercise their affinities and to combine ac- 
:ordingly. 

The composition of the new products, named above, will 
show that they consist only of the old elements differently 
combined. Thus, ivater is composed of oxygen and hydrogen, 
Pyroligneous acid consists of hydrogen, carbon, and oxygen; 
evipyremnatic oil of carbon, hydrogen, and oxygen; carbonic 
acid of carbon and oxygen ; carburetted hydrogen of carbon 
and hydrogen; and ammonia consists of nitrogen and hydro- 
gen. With the exception of ammonia, therefore, these several 
products are constituted of only three elements, their differ- 
ence being the result of the different proportions in which 
they combine, or, in two instances, of the absence of an ele- 
ment. 

On subjecting different vegetables to ultimate analysis, by 
destructive distillation, it has been found that the products, 
which result from the different combinations of oxygen and 
hydrogen are as follows. 

A vegetable substance is ahvays acid, when the oxygen 
which it contains is to the hydrogen in a proportion greater 
than is necessary to form water, or where there is an excess 
of oxygen. 

A vegetable substance is resinous, oily, or alcoholic, when 
the oxygen is to the hydrogen in a less proportion than in 
water, or where there is an excess of hydrogen. 

A vegetable substance is neither acid nor resinous, but 
saccharine or mucilaginous, when the oxygen and hydrogen 
are in the same relative proportions as in water, or where 
there is no excess of either oxygen or hydrogen. 

In oil, resin, alcohol, sugar, and mucilage, there is a quan- 
tity of carbon, in addition to the oxygen and hydrogen. 



Wimi are ihe elements of the several compounds obtained by the destructive distillation 
of vegetables 7 In a vegetable acid, is the proportion of oxygen greater or less than is 
necessary to form water 1 What vegetable substances are formed when there is an ex- 
cess of hydrogen 7 In what proportions are the hydrogen and oxygen in saccharine and 
mucilaginous substances 1 

26* 



306 ouM. 

Ingredie?Us of Plants. 

The ingredients of plants are distinct substances, formerl 
by their secreting organs, and separable from each other with- 
out destructive distillation. They are separated by certain 
solvents, which have the power of dissolving some, but not 
others. Thus, water dissolves the gum but not the resin, 
while alcohol takes up the resin and leaves the gum. The 
solvents employed for these purposes are hot and cold water, 
ether, alcohol, and some of the acids. 

The following are the principal ingredients, or what are 
called the proximate principles of plants ; viz. 



Gum 


Fixed oil 


Sugar 


Volatile oil 


Starch 


Camphor 


Gluten 


Resins 


Extractive 


Narcotine 


Lignum 


Bitumen 


Tannin 


Vegetable alkalies 


Coloring matter 


Vegetable acids. 


Wax 





:% 



j 



We shall examine the properties of only the most important 
of these principles. 

r * 

(jrums. 

Gum Arabic may be taken as an example of pure gum. 
I't dissolves in Avater, wdth w^hich it forms a viscid solution, or 
mucilage, from w^hich it may be obtained in its original state, 
by spontaneous evaporation. It is insoluble in alcohol, or 
ether, the former precipitating it from the watery solution in 
the form of white flakes. Gum is decomposed by sulphuric 
and nitric acids. By the former, it is resolved into water, 
acetous acid, and charcoal; the latter produces with it oxalic 
and malic acid. When gum is submitted to destructive dis 
tillation, it affords w^ater, carbonic acid, carburettcd hydro 
gen, empyreumatic oil, and acetic acid. 



Wliat are the ingredients of plants 7 How are the ingredients of plants separated from 
each other 7 What are ilie principal ingredients, or proximate principles, of plants 7 Id 
what liquid is giiin soluble 7 Into what substances is gum resolved by sulphuric acidt 
What axe the products of gum, wnen submitted to destructive distillation 7 



• UGAR. 307 

Sugar. 

Sugar is chiefly obtained from the sugar cane, a plant 
which grows in hot climates, and which yields it in a larger 
proportion than any other substance. It is also procured from 
the sugar maple, by boiling down the sap which flows from in- 
cisions made in the tree ; and from several roots, particularly 
the beet, from which large quantities are made in France. 

In the manufacture of sugar from the cane, the first pro- 
cess consists in obtaining the juice, which is done by grind- 
ing and pressure. This is then evaporated by a gentle heat, 
during which a quantity of lime is added, partly for the pur- 
pose of neutralizing any free acid, and partly for the purpose 
of separating extractive matter, which unites with the lime^ 
and forms a scum on the surface of the liquid. The evapora- 
don is continued until it acquires the consistency of syrup, 
when it is transferred into wooden coolers, where a portion 
concretes into a crystalline mass, and in this state forms what 
IS called muscovado or raw sugar. It is then placed in ves- 
sels with apertures in the bottom, where the more fluid parts 
drain ofij and form the well known sw^eet syrup, molasses. 

Raw sugar is refined b^he following process : The su- 
gar being dissolved in water, is mixed with the Avhites of 
eggs, or the serum of blood, and boiled. The albumen or 
serum is thus congulated by the heat, and rising to the sur- 
face, brings with it such impurities as the sugar contained, 
which are removed by a skimmer. When the syrup is judged 
to be sufficiently clear, it is placed in smaller pans, and far- 
ther concentrated by boiling, and then transferred into Gool^ 
ers, where it is agitated with wooden oars, until it appears 
thick and granulated. It now becomes white, and the crystals 
being broken by the agitation, facilitates the drammg off of 
the colored matter which remains. 

It is next placed in conical cups of earthenware, of the 
well known form called sugar loaf. These kavmg aper- 
tures at the bottom, a portion of molasses drains off, leaving 
the sugar much whiter than before. Lastly, a quantity of 
pipe clay is mixed with water to the consistency of cream, 



V.'fiat are the principal vegetables from which sugar is obtained 1 WTiat is the pro- 
- I'V wliich sugar is extracted from sugar cane 7 Why is lime added to the juice of 
cane when boiling? What is muscovado sugar 7 How is mola-sses obtained ? How 

.mw sugar refined 7 What is the use of th'j albumen and eerum a-^e^l in this proram'i 



308 GLUTEN\ 

and poured on the loaves to the thickness of an inch. Thw 
water from this slowly percolates through the loaves, ana 
washes all remains of the coloring matter from the sugar. 
The loaves are then dried by heat, and put in papers for 
sale. 

Refined sugar undergoes no change when exposed to the 
air, the dampness of raw sugar being caused by impurities. 

Sugar is decomposed by the sulphuric and nitric acids. 
By analysis it is resolved into the usual constituents of vege 
tables, oxygen, carbon, and hydrogen. 

Starch. 

Starch is an abundant principle in the vegetable kingdom, 
being one of the chief ingredients in most sorts of grain, and 
in many roots and seeds. The process for obtaining starcli 
consists in diffusing the powdered grain or rasped root m 
pure cold water, by which the water is rendered white anc 
turbid. After some hours, the grosser parts, which in vv'heai 
consists chiefly of gluten, are separated by straining, and the 
water which passes through, being placed in shallow vessels 
deposits the starch, on standing. It is afterwards washed anc 
dried with a gentle heat. ^ 

If starch be boiled for a conMderablc time in water con 
taining about a twelfth of its weight of sulphuric acid, it is 
converted into sugar. By careful analysis, it has been fcunc 
that the only difference between the composition ofstarcl 
and sugar, is, that the starch contains less hydrogen and oxy 
gen, in proportion to the carbon, than sugar. How the acic 
acts to convert the starch into sugar, has not been satisfacto 
rily explained. During the germination of seeds, a similai 
change is effected, the starch being in part converted intc 
sugar. 

The principal varieties of starch, are arrow-root, potato 
starcii, sago, tapioca, cassava, salop, and the starch o 
wheat. 

Gluten. 

Gluten may be obtained from wheat flour, by forming i 
into a paste, with cold water, and continuing to wash thij 



How is the sugar purified and whitened after it is placed in the conical cups 7 Wha 
w said of the abundance of starch in the vegetable kingdom 1 What is the process fo 
obtaining starch 1 How may starch be converted into sugar 1 What is the diflerenc' 
between the composition of starch and sugar 7 What are the principal varieties of starch 
How may gluten be obtained 1 



COLORING MATTER. 309 

' ] paste under a stream of the same fluid, as long as any thing 

■ is carried away. The starch being thus removed, a tough 

elastic substance, of a gray color, will remam, which is 

• [ gluten. 

1 This substance has no taste, and is insoluble in water, 

alcohol, or ether, but is soluble in alkalies and acids. If left 

I to undergo the putrefactive fermentation, it emits an offensive 

i \ odor similar to animal substances, and from this circumstance 

it is ap] arent that it contains nitrogen, which indeed is proved 

by its yielding ammonia at a red heat. 

Of all substances, wheat contains the greatest proportion 
of gluten, and it is owing to this circumstance, that wheat 
'* \ flour is more nourishing than that of other grain, gluten be- 
» j ing the most nutritive of all vegetable substances. It is also 
^ I owing to the presence of this substance in the flour, that the 
i \ dough is tenacious, and the bread spongy, or light, the car- 
>: t bonic acid formed during the fermentation of the dough, 
5 i being detained by the gluten, in consequence of which, the 
^ t whole mass is distended, with bubbles of air. 
h Wheat contains from 18 to 24 per cent, of gluten, the re- 
s ^ mainder being principally starch. 

Extractive Matter. 

Most vegetables, when infused for a time in hot water, 

• I impart to it a brown color. When such solutions are evapo- 

rated, there remains a solid substance, of a brownish, or some- 
times of a yellowish color, which is extractive m.atter. 

Extracts are prepared by apothecaries, as a means of con- 
centrating the virtues of plants for medicinal purposes. These 
extracts not only contain the proper extractive matter, but 
several foreign substances also, such as resin, coloring matter 
oil, &c. 

Coloring Matter 

The coloring matter of vegetables is chiefly red, blue, 
green, yellow, or mixtures of these colors. Nearly all vege- 
table colors are discharged by the continued action of light, 



What is the appearance of gluten 7 What are some of the properties of gluten 7 Why 
is wheat flour said to be more nourishing than that of other grain 7 In what manner 
does the gluten in the dough produce the sponginess of the bread 7 WTiat is extractive 
matter 7 W^hat are the principal tints of the coloring matter of vegetables 7 What effect 
ioes light have on the coloring principle of vegetables 1 



310 TANNIN. 

and without exception, they are aP destroyed by the action 
of chlorine. 

Acids and alkalies either destroy, or change the tints of 
vegetable colors. 

The extraction of the coloring principles, and the trans- 
fer of them to different substances, constitutes the art of dye- 
ing, an art which, in the succession of ages, has been carried 
to a high degree of perfection. This art has been practised 
from the remotest antiquity ; for the history of man informs 
us, that from the king on the throne, to the savage in the 
wilderness, all have ever been fond of decorating themselves 
in a variety of colors. 

Colors have been divided into substantive and adjective 
Substantive colors are such as do not require the interven- 
tion of any other substance to fix them permanently, their 
attraction for the cloth being sufficient for this purpose. 
Adjective colors require the intervention of some substance, 
which has an affinity both for the coloring matter, and the 
stuff to be dyed. This intervening substance is called a 
mordant. The mordant generally consists of a metallic salt 
dissolved in w^ater, with which the cloth is impregnated, aftei 
which it is passed through the solution of coloring matter 
The mordants most commonly employed, are muriate of tin, 
sulphate of iron, acetate of iron, and sulphate of alumine. 

Different mordants are used for different colors, and dif- 
ferent kinds of cloth. Thus, black is made with sulphate 
of iron, nutgalls, and logwood. Yellow, with alum, fustic, 
and saffron ; red, of cochineal, madder, red w^ood, or archil, 
with muriate of tin, or sulphate of alumine for a mordant. 
Blue is made with indigo, &c. 

Tannin 

Tannin is the substance, by the absorption of which, the 
skins of animals are converted into leather. This substance 
is contained abundantly in nutgalls, in the bark of many 
trees, particularly the oak, hemlock, and birch, and in most 
vegetable substances which are astringent to the taste. 

Tannin may be obtained from any of these substances, 
by first bruising the article, and then digesting it in a small 



What are the efftcts of chlorine on these colors 1 What constitutes the art of dyeing? 
How are colors divided'? What are substantive colors'? What are adjective colors 7 
What are mordants in coloring'? What are the principal substances used as mordants! 
What 18 tannin 7 What are the principal substances which contain tannin 7 How may 
tannin be ootainedl 



VEGETABLE OILS. 31 1 

quaniity of cold water, and afterwards evaporating the water. 
This substance is of a yellowish brown color, extremely 
astringent to the taste, and soluble m w^ater and diluted al- 
cohol. 

Tannin is distinguished by its affording an insoluble pre- 
cipitate with isinglass, or any other animal jelly. It is on 
this principle that the art of tanning leather is founded. The 
hides are laid in vats, and between them there is thrown a 
layer of oak or other bark, which contains tannin, in coarse 
powder. The tannin of the bark is first dissolved by the 
water and afterwards combines with the leather, by which it 
is rendered hard, and nearly impervious to water. 

Vegetable Oils. 

The vegetable oils are of two kinds. Fixed and Volatile. 

Fixed Oils. These are found only in the seeds of plants, 
and chiefly in such as have two cotyledons, such as almonds, 
linseed, walnuts, and rapeseed. The oil of olives, however, 
is extracted from the pulp which surrounds the kernel. 

The fixed oils are obtained by crushing or bruising the 
seed, and subsequent pressure. They are viscid, nearly in- 
sipid, and inodorous, and generally congeal at a temperature 
considerably higher than 32 degrees. 

The fixed oils, with a few exceptions, undergo little other 
change, by exposure to the air, than those of growing more 
viscid, and acquiring a degree of rancidity. The latter 
change is owing to the absorption of oxygen, for rancid oils 
redden vegetable blues, showing that they contain a quantity 
of free acid. 

The absorption of oxygen, by some of the fixed oils, and 
particularly by those of linseed and rapeseed, is sometimes 
so abundant and rapid, as to set fire to light porous substan- 
ces on which they are spread. 

These are called cases of spontaneous combustion, and in 
many instances, w^here these oils have been suffered, either 
by accident or otherwise, to come in contact with cotton wool, 
or cotton cloth, destructive fires have been the consequence. 

The alkalies combine with the fixed oils, and form soap. 



How is tannin distinguished? On what principle is the tanning of leather founded 7 
Wliat are the two kinds of vegetable oils ? In what parts of plants are the fixed oib 
found 1 l.fow are the fixed oils obtained 7 W^hat changes do these oils undergo by ex- 
posure to the air ? What causes oils to become rancid 7 In what manner do these oils 
sometimes produce spontaneous combustion 7 



312 RESINS. 

The composition of all these oils is carbon, and hydrogo 
and oxygen. 

Volatile Oils. Plants and flowers owe their odor and fli 
vor to volatile or essential oils. These oils are obtained t 
distilling the plants which contain them with water. The \vi 
ter prevents the plant from being burned. Both pass ini 
the receiver from the still, where the oil is found either at tl 
bottom, or on the surface, as its density is greater or less tha 
that of water. Some fruits, however, yield essential oil I 
pressure ; such are the orange, the lemon, and the bergamc 
which contain it in vesicles in the rind of the fruit. 

The odor of the essential oils is aromatic, and their tas 
penetrating. They consist of the odoriferous principle 1 
which plants are distinguished from each other in a conce 
trated state. These oils are soluble in alcohol, and vei 
sparingly so in water. When dissolved in the former, th( 
constitute essences, a great variety of which are manufactu 
ed, particularly in Paris, and sold as perfumes in most pax 
of the world. 

All the volatile oils, when pure, pass away by evaporatio 
Hence, a good test of the purity of these oils is to let a dr( 
fall on paper, and if any oily spot is left, after warming tl 
paper, the essential oil has been adulterated by some fix< 
oil. 

The essential oils burn with a clear, white light, and tl 
only products of their combustion is water and carbonic aci 
Hence, these oils are composed solely of carbon and h3'di 
gGXi, the water and carbonic acid being formed by the a 
sorption of oxygen to support the combustion. 

. j 
Resins. 

The resins are peculiar substances which exude from C( 
tain trees, or plants, or are contained in their juices. Th* 
commonly contain a portion of the essential oil of the pjai 
They are solid at common temperatures, and, when rubb( 
show signs of electrical excitement. Their colors are y 
low, reddish, and white, and most of them are transluce: 
or transparent. 

The resins are soluble in alcohol, ether, and the essent; 



\Vliat are the resins 7 In what liquids are the resins soluble 7 



L 



RESINS. 313 

oils, but are precipitated ty water, in which they are entirely 
insoluble. They are dissolved, and at the same time decom- 
posed, by the sulphuric acid, with evolution of sulphuric acid 
2:as, and the deposition of charcoal. 

The principal resins are, common resin, gum copal, Jac, 
mastic, elemi, and dragon's blood. Common resin, called 
rosin, is what rem.ains after the distillation of spirit of turpen- 
tme. The turpentine itself is obtained by making incisions 
in the fir tree, from which it exudes. This consists of resin 
and the oil of turpentine, which are separated by distillation. 

The use of many of the resins are well known. Sealing 
wax is made of lac, turpentine, and common resin. Copal 
and elemi, when dissolved in spirit of turpentine, or alcohol, 
form varnishes. 

Fermentation. 

Fermentation consists in a spontaneous exercise of chemi- 
cal affinity, in a vegetable substance, or solution, in conse- 
quence of which its properties are materially or totally 
changed. 

There are several kinds of fermentation, the names of which 
indicate the products formed. These are, the saccharine, the 
vinous, the acetic, and the putrefactive. 

The product of the first, is sugar; that of the second, wine : 
rhat of the third, vinegar; while the fourth results in the total 
decomposition of all vegetable matter, and the destruction of 
every useful product. 

Saccharine Ftrmentatio7i. The germination of seeds, and 
the malting of barley, are instances of the saccharine fermen- 
tation, the farinaceous being converted into saccharine m.at- 
ter, or sugar. 

Vinous Fermentation. This, by the generality of mankind, 
is considered the most important of all fermentations, since, 
from the days of Noah and Alexander to the present time, 
its product has been employed, either to heighten the plea- 
sures, or as an antidote to the cares of this poor life. 

Wine, as well as other intoxicating liquors, are produced 
only by the vinous fermentation ; a process by which alcohol 



Wh.y are the resins precipitated by water? What are the names of the principal resins'? 
In what manner is common resin, or rosin, obtained 1 "What are the uses of some of the 
principul resins ? Wiiat is fermi3ntation 7 What are the cMerent kinds of fermentation 1 
VyTiat is the product of the saccliarine fermentation 7 Wliat the product of tlie vinoiis 1 

27 



314 FERMENTATION. 

is formed. There are four conditions necessary to the suc- 
cess of this process. These are, the presence of water, sugar, 
and yeast, in mixture, and a temperature between 60 and 70 
degrees. Or, instead of yeast and sugar, saccharine matter, 
and starch, or the sweet juices of fruits. These conditions, 
being united, there succeeds a brisk intestine motion, attend- 
ed with the escape of carbonic acid gas in abundance, and at 
the same time the transparency of the fluid is diminished by 
the rising of opaque filaments, the whole being attended with 
an elevation of temperature. When these phenomena cease, 
the liquor is found to have lost its sweet, mucilaginous taste, 
and to have acquired some degree of acidity, with a brisk, pe- 
netrating flavor, and the power of producing intoxication. 

In respect to the chemical changes which take place du- 
ring this process, it is found that after the fermentation, the 
sugar has entirely disappeared, and that it is replaced by a 
quantity of alcohol, none of which existed in the liquid before 
the process. Hence sugar is converted into alcohol by the 
vinous fermentation. But the weight of the alcohol is never 
equal to the weight of sugar employed, by nearly one half. 
This loss is accounted for by the escape of the carbon and 
oxygen of the sugar, in the form of carbonic acid. When the 
process is conducted in such a manner that the quantity of 
carbonic acid can be retained and weighed, it is found to cor- 
respond precisely with the loss of the alcohol ; that is, the 
com.bined weight of the acid and alcohol are equal to that of 
the sugar. This may be made apparent thus : Sugar and 
alcohol are composed of 

Sugar. Alcohol. 

3 proportions of carbon 18 2 prop, carbon 12 
3 do. of hydrogen 3 3 do. hydrogen 3 
3 do. of oxygen 24 1 do. oxygen 8 



45 23 

This shows a loss of one proportion of carbon and two 
proportions of oxygen from the sugar, the alcobol contain- 



What is the product of the acetic 1 What are the results of the putrefactive fermenta- 
tion 7 What changes do seeds and barley undergo by germination and malting 1 Wlial 
are the four conditions necessary to induce the vinous f^^rmentation ? W^hat gas escapes 
during this fer.ncntation 1 What becomes of the sugar during the vinous fermentation ? 
Is the weight of alcohol formed, equal to the weight of sugar employed 7 What becomea 
of the deficiency 7 What is the composition of sugar 7 What is the composition of alco 
hoi 7 How does it appear that the lo?s froni the sugar escapes in the form of rarbonic 
acid? 



ALCOHOL. 315 

mg only two parts of carbon and one of oxygen, while the 
sugar contained three of carbon and three of oxygen, the pro- 
portion of hydrogen being the same in both. The difference 
between the number for sugar and that for alcohol is there- 
fore 22. Now we have seen that carbonic acid is composed 
of one proportion or atom of carbon 6, and two proportions 
or atoms of oxygen 16, and these two numbers make the 
precise quantity of carbon and oxygen lost by the sugar,^nd 
which is not contained in the alcohol. Therefore, 45 parts 
of sugar produce by fermentation, 23 parts of alcohol, which 
is found in the fermented liquor, and 22 parts of carbonic 
acid gas, which escape. 

This investigation, while it affords a beautiful illustration 
of the doctrine of definite proportions, demonstrates that 
nothing is lost by a new arrangement, or interchange of ele- 
ments. 

It is believed, that the vinous fermentation never takes 
place without the presence of sugar, the elements of this 
ingredient, as shown above, furnishing by decomposition 
those of the alcohol. In cases where substances which con- 
tain no sugar are know^n to produce alcohol without the ad- 
dition of this ingredient, the process is explained by the sup- 
I position that the starch which these substances contain, is 
' converted into sugar by the saccharine fermentation. It is 
well known that potatoes, w^hich contain little, or no sugar, 
yield a large quantity of alcohol by fermentation. But po- 
tatoes contain a large proportion of starch, which entirely 
disappears during the process, being first converted into su- 
gar, and then into alcohol. 

Alcohol. 

When a liquor which has passed through the vinous fer- 
mentation is distilled, there rises from it a fluid, having much 
more highly intoxicating powers than the fermented liquor 
* from which it is obtained. This liquor has a sharp penetra- 
Uing taste, and retains the flavor and odor of the fermented 
; liquor, from which it is distilled. The fluid so obtained is 
alcohol mixed with water, and containing a portion of the 
essential oil peculiar to the vegetable which formed the fer- 



Does the vinous fermentation ever take place without the presence of sugar 7 IIow is 
j the process explained in cases where alcohol is formed by substances containing no su- 
! ga", as in potatoes 1 How are spirituous liquors obtained 1 



816 ETHER. 

mentative solution, and which gives it a flavor. Thus, brandy^ 
rum, and whiskey, have each a flavor of their own, which 
arises from this circumstance. These are called spirituous 
liquors. 

When a spirituous liquor is distilled, the alcohol is obtained 
in a state of much greater purity, the oil which it contained 
and most of the water being left in the retort, or still. In 
this state it is colorless, highly inflammable, produces cold 
by evaporation, and occasions a considerable augmentation 
of temperature by admixture with water. 

Common alcohol contains a portion of water, and has a 
speciiic gravity of from 850 to 875, water being 1000. It may 
be further purified, or freed from w^ater, by adding to it warnj 
carbonate of potash, or muriate of lime, Avhich combines wati 
the water, and sinks to the bottom of the vessel, after whicl 
the alcohol may be poured off Very pure alcohol may alsc 
be procured, by putting it into a bladder, which being suS' 
pended in a warm place, the w^ater will slowly pass througt 
the coats, while the pure alcohol is retained. The stronges' 
alcohol which can be procured by either of these methods 
has a specific gravity of 800, or 796, at the temperature o. 
60 degrees. 

Pure alcohol has never been frozen, though exposed to th( 
lowest temperature which art has ever produced. It is £ 
powerful solvent, being capable of dissolving camphor, resins 
soap, volatile oils, sugar, balsam, &c. 

Pure alcohol has precisely the same properties, from what 
ever substances it is obtained. 

Ether. 

The name ether was originally applied to a highly fragran" 
and volatile liquid, obtained by the distillation of alcoho' 
with sulphuric acid. But it has been found that the same 
substance, when distilled with other acids, aflx)rds a liquic 
possessing in some respects similar properties, and therefore 
these compounds are now distinguished by prefixing the 
name of the acid employed. 



What gives the peculiar flavor to distilled liquors, as brandy, rum, and whiskey 
How is alcohol obtained 1 Do spirituous liquors yield pure alcohol on distillation 7 Wha 
is the specific gravity of common alcohol 7 How may pure alcohol be obtained 7 Wha 
Is the specific gravity of the purest alcohol 7 What is said of the freezing of pure alr/» 
hoi 7 What is said of the solvent powers of alcohol 7 How is ether obtained 7 



ETHfitt. 317 

Sulphuric Ether. To make sulphuric ether, pour into a 
fubulated retort a certain quantity of alcohol by weight, and 
add, in small portions at a time, the same weight of strong 
sulphuric acid, allowing the mixture to cool after each addi- 
tion. Then connect the retort with a receiver, and, by means 
of a lamp, make the mixture boil. The receiver must be kept 
cold by the application of ice, or wet cloths. The ether will 
pass over and be condensed in the receiver. The ether thus 
obtained, contains a portion of alcohol, and commonly a 
little sulphuric acid, from which it is purified by agitation 
with potash, and redistillation. 

In respect to the chemical changes which take place be- 
tween the alcohol and acid, to form the new product ether, 
it is found, on analysis, that the latter substance is composed 
of two proportions of olefiant gas, and one proportion of 
water. The number for olefiant gas being 14, and that for 
water being 9, the equivalent number for ether is 37. 

Now olefiant gas consists of 2 atoms of carbon 12, and 2 
atoms of hydrogen 2=^14, to which 1 atom of water 9, being 
added, makes the composition of ether. 

Alcohol is composed of, or contains the elements of, 1 atom 
of olefiant gas, and 1 atom of water, and therefore alcohol 
contains double the proportion of v/ater that ether does. 
Now if 1 proportion or atom of w^ater be abstracted from two 
of alcohol, the exact proportions constituting ether will re- 
main. Thus, the number for alcohol being 23, double this 
number is 46, from which one atom of w^ater, 9, being taken, 
there remains 37, the number representing ether. It w^ill 
be seen, on comparing these several numbers, that they ex- 
actly correspond with the constituents above named, and it 
is supposed that this is the precise mode in w^hich sulphuric 
acid operates to convert alcohol into ether. In consequence 
of the affinity of sulphuric acid for water, it abstracts one 
atom of that fluid from the alcohol, and thus the elements of 
ether remain. 
. Sulphuric ether is a light, odorous, transparent fluid, of a 
hot and pungent taste. Its specific gravity, w^hen most pure, 
is about 700, water being 1000 ; but that of the shops is 740, 
or 750, owing to the presence of alcohol. When exposed to 



What is the process of obtaining sulphuric ether t What is the composition of sul- 
phuric ether "^ Explain the difference between alcohol and ether, and describe the change 
by which the former is converted into the latter. What is the specific gravity of ether 
when moet pure "? How does ether occasion an intense degree of cold l 

27* 



318 VEGETAbLfe ALKALIES 

the open air, it evaporates with great rapidity, and occasions 
an intense degree of cold. This is in consequence, of the 
principle already explained, that when a substance passes 
from a denser to a rarer state, caloric is absorbed. 

Ether is exceedingly combustible, and burns with a blue 
flame, the product of its combustion being water and car- 
bonic acid. 

Ether is employed as a medicine in nervous fevers, and as 
a solvent in the arts. When pure, or when that of the shops 
is agitated with water, and, after standing a while, is poured 
off, it is a solvent of India rubber, one of the most insoluble 
of vegetable products. 

Nitrous Ether is prepared by distilling alcohol with nitric 
acid, in a manner similar to that described for sulphuric 
ether, to which its leading properties are similar. It is, how* 
ever, still more volatile^ and is subject to decomposition by 
keeping. 

Vegetable Alkalies. 

Potash and soda were formerly called vegetable alkalies, 
in order to m.ark their origin, and to distinguish them from 
the other alkaline substances. These alkalies, as stated in 
their proper places, are obtained chiefly by the incineration 
of land and sea plants, though they both exist ready formed 
by nature. They are found to be metallic oxides, and have 
been described under the names of oxide of potassium and 
oxide of sodium. The vegetable alkalies now to be descri- 
bed, are strictly vegetable products, and are obtained, not by 
incineration, but by the digestion, or maceration, of certain 
vegetable substances in water. 

The following is an outline of the method by which they 
are obtained. In the first place, the substance containing 
the alkali is digested in a large quantity of very pure water, 
which dissolves the salt, the base of which is the alkali. 
On adding some salifiable base, such as potash, or ammonia, 
which has a strong afiinity for the acid of the vegetable salt, 
in the watery solution, this salt is decomposed, its acid com- 
bining with the potash, or ammonia, and thus leaving the 
vegetable alkali in the solution. This being insoluble, while 



Why does the evaporation of ether occasion cold 7 What are the uses of sulphuric 
ether 7 How is nitrous ether procured? How does the nitrous differ from the sulphuric 
ether 1 How do the oxides of potassium and sodium differ from the vegetable alkalies! 
How are the vegetable alkalies obtained 1 Give an outline of the process by which these 
•ubstances are procured. 



MORPHIA. 819 

the new salt is soluble in water, is collected and washed on 
a filter. The vegetable alkali thus obtained, is however im- 
pure, and requires to be dissolved in alcohol, with the addi- 
tion of some animal charcoal, which deprives it of its color, 
— ^then filtered, and the alcohol evaporated, when the pure 
alkali will be obtained. 

The most important vegetable alkalies are^ Morphia, Ci?i' 
choiiia^ and Quitiid. 

Morphia. 

Morphia is the narcotic principle of opium. Opium, be 
sides morphia, contains meconic acid, narcotine, gum, resin 
oils, extractive, and colouring matter, and a small quantity of 
caoutchouc, or India rubbet. 

Morphia exists in the opium, combined with meconic acid, 
forming meconate of morphia. To obtain it, therefore, it is 
necessary to decompose this salt, by which the morphia is li- 
6erated, and afterwards obtained by the evaporation of some 
fluid in which it is soluble. 

This is done by boiling a solution of opium in \^'ater, with 
magnesia, by which the meconate of morphia is decomposed, 
and a meconate of magnesia is formed. The morphia being 
thus precipitated, is obtained in an impure state by filtration, 
and afterwards purified by solution in alcohol. On evapo- 
rating the alcohol, the pure alkali is deposited in crystals. 

Pure morphia occurs in small rectangular white prisms, 
of considerable lustre. It is insoluble in water, but alcohol, 
especially by the aid of heat, dissolves it freely. In its pure 
state, this substance is nearly tasteless, owing to its insolubi- 
iity in water, but Avhen it is rendered soluble by combining 
with an acid, or when dissolved in alcohol, it is intensely bit- 
ter. From the same cause, in its pure and solid state, mor- 
phia is nearly inert on the living system, Orfila having given 
twelve grains to a dog, without any sensible effects. On the 
contrary, when in a state of solution, it acts on the system 
with great energy, Orfila having seen alarming effects from 
half a grain. 



^Vllal are the most important vegetable alkalies 7 Whai is morphia 1 What are the 

ingredients in opium besides morphia'? In what state does morphia exist in the opium 1 

WhdX is the process for obtaining morphia 1 What is the use of the magnesia in this 

t firocess 1 What are the solvents of morphia 7 In what etate is morphia used in medicine? 



320 ClNCHONlA AND QUINtA. 

The best method of using morphia m medicine, is to forni 
with it an acetate, or a citrate, both of which are soluble in 
water, and alcohol. In either of these states, it is given ir 
those cases where opiates are required, and it produces al 
the soothing effects of opium, without the disagreeable conse 
quences which often follow the administration of that drug. 

Narcotine. This substance, though not an alkali, is con 
tained in opium, and is therefore properly noticed here. 

Narcotine is obtained by digesting opium in water, anc 
evaporating the solution to the consistence of extract, an( 
then digesting this with sulphuric ether. The water, as showi 
above, will hold in solution meconate of morphia, as well a: 
narcotine, but the meconate is insoluble in ether, which onl; 
takes up the narcotine. On evaporation, the ether so treatec 
will deposit small particles of narcotine. 

This substance is little soluble in water, either cold or hoi 
but dissolves in oil and alcohol. 

The unpleasant properties of opium as a medicine, are at 
tributed to this substance, and perhaps the different effects o 
the salts of morphia from opium, are only owing to their no 
containing narcotine. 

Cinchonia and Quinia. 

It has been fully established, that the efficacy of cinchonia 
or Peruvian bark, in the cure of fevers, resides in the alka 
lies, called cinchonia and quinia. These two principles 
though quite analogous in many respects, are distinct sul: 
stances, and appear to bear the same relation to each othe 
as potash and soda. Cinchonia exists in the pale bark, quini; 
in the yellow, and both are present in the red bark. 

They are obtained from these substances by a proces 
similar to that already described for separating morphia fror 
opium. 

Cinchonia appears in white crystalline grains, which ar 
nearly insoluble in water, but which are readily taken up b 



Why is it not used in its pure state ? What advantage has morphia over opium as 
medicine? How is narcotine obtained? Is narcotine soluble In water? What are th 
solvents of narcotine ? What effects of opium are imputed to narcotine 7 What is sai 
of the efficacy of cinchonia and quinia in the cure of fevers 1 What relation do cinch* 
nla and quinia appear to bear to each other 7 In what species of bark do these alkali< 
txist 1 By what process are these substances otrtained 7 What is the ap^warancc i 
etnclumSal 



ANIMAL CHEMISTRY. 321 

(Killing alcohol. Its alkaline properties are well marked by 
its power of neutralizing acids. It forms nitrates, muriates, 
8ulphates, acetates, &:c., all of which are soluble in water. 

Qidnia is a white, porous substance, of a flocculent ap- 
pearance. It does not, like cinchonia, form crystals. It is 
also nearly insoluble in water, but dissolves freely in alcohol, 
affording an intensely bitter solution. Like cinchonia, it has 
strong alkaline powers, and forms salts with the several 
acids. Its febrifuge effects are much more decisive than 
those of cinchonia, and it is now extensively employed in the 
practice of medicine, in the form of the sulphate of quinia 

This salt crystallizes in delicate white needles. It contams 
90 parts of the quinia combined with 10 of the acid. 

The composition of cinchonia and quinia is thus stated by 
Pelletier and Dumas, 

Cinchonia. Quiniau 

Carbon 76.97 Carbon 74.14 

Oxygen 7.97 Oxygen 6.77 

Hydrogen 6.22 Hydrogen 8.80 

Nitros^en 9.02 Nitrogen 10.76 



100.18 100.47 

The composition of these alkalies, therefore, consist of the 
Lame elements, and nearly in the same proportions, 

ANIMAL CHEMISTRY. 

In relation to chemistry, the circumstances which distin- 
gfuish animal from vegetable substances, are the large quan- 
tity of nitrogen which the former always contain, their strong 
tendency to putrefaction, and the offensive products which 
they exhale during decomposition. 

Animal substances are essentially composed of carbon, 
hydrogen, oxygen, and nitrogen ; and in addition to these, 
they sometimes contain sulphur, phosphorus, iron, and small 
quantities of saline matter. 

Fibrin. — The lean parts of animals consist chiefly of fibrin 



How do the alkaline properties of cinchonia appear? What salts does it form with 
acids'? What is the appearance of quinia I What is the solvent of quinia? In what 
form is quinia employed in medicine? What is the appearance of sulphate of quinia, 
and what its composition? In relation to chemistry, what are th^ circumstances which 
distinguish animal from vegetaljle suhstances ? What is the essential composition 0/ 
•lumal Kibf *aiices t 



322 ' ANIMAL CHE3IISTRY. 

This may be separated and observed in its pure state, by re 
moving the soluble parts of lean beef, cut into small pieces, 
by repeated washing, and digestion in cold water. 

Fibrin thus obtained, is nearly white, and is insipid and 
inodorous. It readily passes into the putrefactive fermenta- 
tion, but in thin pieces, suspended in a dry place, its fluid 
parts evaporate, and it becomes hard, brittle, and translucent. 

Alcohol converts fibrin into a fatty substance, which is so- 
luble in the same fluid and in ether, but is precipitated by the 
addition of water. This substance is decomposed by all the 
strong acids, and is dissolved by caustic potash. 

Fibrin is composed of 18 parts of carbon, 14 of hydrogen, 
5 of oxygen, and 3 of nitrogen. 

Albumen. — Albumen enters largely into the composition of 
animals. Their solid, as well as fluid parts, contain it in 
greater or less proportion. Liquid albumen is nearly pure 
in the whites of eggs. Its appearance, and many of its pro- 
perties, in this state, are well known. It is coagulated, and 
converted into a soft solid, by heat, by alcohol, and by the 
stronger acids. The character of being coagulated by heat, 
distinguishes albumen from all other animal fluids. It is com- 
pletely soluble in cold water, and it is said that when this fluid 
contains only YTruTr P^^'^ ^^ albumen, it becomes opalescent by 
boiling. On this property is founded the clarifying effect? 
of albumen. As it coagulates, by the heat of the water, il 
entangles any insoluble particles the fluid contains, and rises 
with them to the surface. 

Gelatine. — This substance forms a proportion of all the 
solid parts of animals, and is particularly abundant in the skin 
tendons, membranes, and bones. It is soluble in boiling water, 
and forms a bulky, semi-transparent, tremulous mass, when 
cold. By evaporation, it becomes a solid, brittle, hard, and 
semi-transparent substance, known in commerce and the arts, 
under the name of glue. This is chiefly prepared from the 
cuttings of skins, and the ears and hoofs of animals. Isin- 
glass, which is the purest variety of gelatine, is prepared from 
certain parts of flsh, and especially the sturgeon. The gela- 



What is fibrin 7 How m^ay fibrin be obtained? What are the properties of fibrin 1 
What is the composition of fibrin ? Where is albumen found nearly in a pure state 1 
By what agents is albumen coagulated 1 By what property is albumen distinguished 
from all other animal fluids? Now does albumen clarify liquids 7 In what pares of ani' 
mals is gelatine most abundant? Under wh.it name is dry gelatine known? Whot ^ 
isingla&s ? 



ANIMAL CHEMISTRY. 323 

line called calves foot jelly, is prepared by boiling the feet of 
ihat animal in water. 

Gelatine is precipitated by tannin. This is so delicate a 
lest for gelatine, that it is said, an infusion of nut galls, which 
contains a large quantity of tannin, will show the presence 
of gelatine when mixed with 5000 times its weight of water. 

The three ingredients, fibrin, albumen, and gelatine, form 
the most bulky parts of all animals, that is, the flesh, tendons 
cartilages, and skin 

Oleaginous Substances. 

The fat of animals is very analogous, in its composition 
and proportions, to the fixed, vegetable oils, its ultimate prin- 
ciples being carbon, hydrogen, and nitrogen. 

There is a considerable variety in the appearance and 
qualities of the fatty principle contained in different animals. 
The solid fat of land animals is called tallow, while the cor- 
responding substance from fish, which is fluid at common 
temperatures, is called oil. 

All these substances agree very nearly in respect to com- 
position, the principal difference being in respect to form and 
appearance. Their uses, for making soap, giving light, &c 
are well known. 

Blood. 

The blood of animals obviously consists of two parts, called 
serum and crassamentum. In healthy blood, these two parts se- 
parate spontaneously on standing. The crassamentum coagu- 
lates, and forms a red, solid mass, while the serum surrounds 
it, in form of a yellowish fluid. 

The serum contains a small quantity of soda in a free state, 
and is 29 parts in 1000 heavier than water. It consists, in 
part, of albumen, and is coagulated by heat, acids, and alco- 
hol. The crassamentum consists of iavo parts, the fibrin and 
the colouring matter. The fibrin does not differ, except in 
form, from that obtained from lean flesh, which has already 
been described. 



By what ?ubstance is gelatine precipitated from its solutions % What parts of animals 
are formed by fibrin, albumen, and gelatine 1 What are the ultimate principles of animal 
%tG? What difference is there between animal fats and animal oils 7 In blood what 
is the serum and what the crassamentum 1 Whaf is serum composed of 7 What does 
crassamentum consist of? 



S24 ANIMAL CHEMISTRY. 

The coloring matter of the blood consists of distinct par- 
ticles, which in birds and cold-blooded animals, are elliptical 
in form, but in man and other mammiferous animals, they are 
globular. These facts have been acsertained by means of 
the microscope. The globules are insoluble in the serum, 
but their color is dissolved by water acids, and alcohol. 

It has been suppossed that the crassamentum contained a 
portion of iron, but recent analysis has shown that this metal 
does not belong to the crassamentum as a whole, but only to 
the coloring matter ; for when the fibrin is carefully sepa- 
rated from the coloring principle, it does not contain a 
trace of iron, while iron is always found in the red glo- 
bules. 

From the presence of iron in the globules, and its total 
absence in the other parts of the blood, it is inferred that the 
red color of the globules depend on the presence of this 
metal, though its quantity is found to be only half a grain to 
a hundred grains of the globules. 

It is found that during the coagulation of blood, heat is 
evolved, and consequently its temperature is raised. This 
is owing to it* passage from a rarer to a denser state, in con- 
sequence of which its capacity for caloric is diminished. 
We have had frequent occasions to refer to this principle. 
The increase of temperature from this cause, is however 
very slight, perhaps not more than two or three degrees, but 
its cooling is considerably retarded by the caloric thus 
evolved. 

The blood presents several phenomena, which neither the 
principles of chemisty nor physiology have been able to ex- 
plain. The cause of its coagulation, for instance, has never 
been satisfactorily accounted for. It does not arise for want 
of heat or motion, for if blood be drawn when the tempe- 
rature of the air is equal to that of the animal from which it is 
taken, and then kept constantly in motion, its coagulation 
is not prevented, or even retarded. Indeed, neither mod- 
erate heat, nor cold, a vacuum, nor pressure, nor even di« 
lution with water, seem to have any influence on the coagu- 
lation of the blood. On the contrary, its coagulation is pre- 



What does the coloring matter of blood consist of ? On what metal does the coloring 
matter depend? What proportion of iron is contained in the red globules of the blood! 
What is said concerning the heat evolved by the coagulation of the blood 7 What is said 
concerning the cause of the blood's coagulation 7 what circumstances are said not to af 
fert the cooeulafion of the blood 7 



ANIMAL CHEMJSTRV. 325 

vented by certain causes, the effects of which could not be 
supposed to influence this circumstance. Thus, the blood 
of persons who have been destroyed by some kinds of poison, 
and by mental emotions, has been found uncoagulated, and in 
a fluid state. How causes so unlike should produce the 
same effects, or why either of them should affect the blood 
et all, are equally unknown. 

Respiration. 

Respiration is the act of breathing, and consists in the 
alternate drawing into, and throwing out of the lungs, a 
quantity of atmospheric air. And it appears that this pro- 
cess, or an equivalent one, is necessary to support the lives 
of all animals. 

The atmosphere, as formerly shown, is composed of 80 
parts of nitrogen, and 20 parts of oxygen, and it is found by 
experiment, that no other gaseous compound can be substi- 
tuted for respiration, nor can these proportions be varied with- 
out injury to its qualities. 

The immediate effect of respiration, is to produce a 
change in the color of the blood as it passes through the 
lungs, thus indicating that it suffers some change in its pro- 
perties at the same time. 

The necessity of respiration to all w^arm blooded animals 
requires no proof; and the necessity that the blood should 
be brought into contact with the air inspired, is equally ob- 
vious from the organization of their lungs. 

Such animals are provided with two kinds or classes of 
blood vessels, called veins and arteries. 

The arteries, particularly the large ones, are deeply seat- 
ed within the animal, and convey the blood to all parts of the 
living system. The veins, on the contrary, especially the 
small ones, are situated near the surface, and are destined 
to convey the blood back to the heart, which had been thrown 
out by the arteries. 



What circumstances are said to prevent the coagulation of the blood % What is respi- 
ration 1 What is the composition of the atmosphere 1 What effect does a cnange in the 
composition or proportion of the elements of the atmosphere produce on respiration 
Wliat is the immediate effect of respiration on the color of the blood 1 What is said of 
the necessity of respiration 1 WTiat are the two kinds of blood vessels called 1 Where 
«e the veins aui arteries situated with respect to each other 7 What is the use of the ar- 
teries ? What part of the circulation do the veins perform 1 

28 



326 RESPIRATIOJJ 

But besides these two great systems of blood vessels, 
there is another system called the 'pulmonary, which is des 
tined expressly to convey the blood to the lungs, where it 
undergoes the change above mentioned, and then back 
again \o the heart. 

The entire circulation will now be readily understood. — 
The blood being- thrown to all parts of the body, is returned 
to the right side of the heart by the great system of veins. 
From the right side of the heart it is sent to the lungs, by 
the pulmonary artery, and being there changed into arterial 
blood, is returned by the pulmonary veins to the left side of 
the heart. From the left side of the heart, it is thrown to 
all parts of the body by the great system of arteries, to bo 
returned to the right side by the veins, as before. 

When venous blood, fresh drawn, is suffered to stand a 
few minutes in a confined portion of atmospheric air, it is 
found that the air loses a part of its oxygen, which is re- 
placed by the same volume of carbonic acid gas, and at the 
same tim.e the color of the blood, from being of a dark pur- 
ple, becomes florid red. This is the same change of color 
w^hich the blood undergoes in its passages through the lungs. 
The cause of the change in the lungs might therefore be 
inferred to be the absorption of oxygen by the blood, and the 
subsequent emission of carbonic acid. 

That this change of colour in venous blood, when out of 
he lungs, is owing to the contact of oxygen, is shown by 
the more immediate production of the same effect when 
oxygen is substituted for atmospheric air, and also by the 
fact that no change of color is produced when the oxygen 
is entirely excluded. Hence the inevitable conclusion, that 
fresh drawn venous blood emits a quantity of carbon in con- 
sequence of its coming in contact with oxygen, and that its 
change of color is caused by this emission. 

The same change thus proved to take place in the atmos- 
phere, is constantly going on in the lungs. The venous 
blood, which, as above explained, is sent to the lungs through 
the pulmonary artery, is charged vrith carbon, to which it 



What is the office of the puhno-nary system 1 Explain the entire circulation. From whlr^i 
side of the heart do the great arteries convey the blood to all parts of the body ? How is 
the blood conveyed from the right to the left side of the heart 1 What etfccts do the contact 
of atmospheric air and venous blood produce on each 7 How is it proved tiiat tlio 
change of color in the blood is produced by the oxygen of the air 7 What is the caupc ol 
the change of color in venous blood ? 



RESPIRATION. 327 

ewe? its dark color. The oxyg-en o-f the atmosphere, b}' in- 
spiration, fills all the air vessels of the lungs, and is thus 
brought nearly into contact with the blood, being separated 
from it only by the thinnest membrane. 

It appears that through this membrane, the oxygen of the 
atmosphere is absorbed, and having combined with a portion 
of the carbon of the blood, it is again emitted in the form of 
carbonic acid gas, and to this process is owing the change 
A'om venous to arterial blood. 

In proof of this, experiment shows that when any living 
tnimal is confined in a portion of air containing a known 
quantity of oxygen gas, the oxygen gradually disappears, 
md is replaced by the same quantity of carbonic acid. In 
ordinary respiration, the air from our lungs always contains 
a portion of carbonic acid. This is proved by merely blow- 
ing into a glass vessel containing a solution of lime in ^vatei:, 
or whafis commonly called lime 'water, ^Yhen the cle^T Avater 
will instantly become turbid, because the carbonic acid from 
tlie lungs unites with the lime of the water, and forms an in- 
soluble carbonate. 

It does not appear that the oxygen is absorbed, and retain- 
ed by the blood, for the absolute quantity of air, though 
many times respired by a confined animal, remains the same. 
7 his also proves that the nitrogen of the atmosphere is not 
absorbed. It is well known by experiment, that the conver- 
sion of oxygen gas into carbonic acid, does not in the least 
change its volume, but only adds to its weight. This ac- 
counts for the reason why the volume of air is not changed 
by respiration, or by convertion into carbonic acid, provided 
no absorption take place. 

Thus the change from venous to arterial blood, seems to be 
produced entirely by the lo^s of carbon, which the former 
suflTers w^iile passing through the lungs. 

It appears also, from numerous experiments, that not only 
waim blooded animals, but also fish, and cold blooded reptiles 
of the lowest order, absolutely require the presence o* 



To wha-t IS the dark colour of venous blood owing % Whai cha.nge does the blood 
undergo in the lungs 7 How is it proved that oxygen is converted into carbonic acid in 
the lungs 1 How is it proved that we emit carbonic acid at every expiration 1 In respi- 
ration, is the oxygen absorbed and retained by the bloofl, or not? How does it appeal 
that neither the nitrogen nor the oxygen of the atmosphere is retained in the process a 
respiration 7 In what does the change from venous to arterial blood consist ? \\Tiat is 
££id ofthfi oftcessitv ofozygen to supponth^ lives cf coJd blaodod reotilcs? 



28 ANIMAL HEAT, 

oxygen in crrder to sustain life. Water, it has already be .n 
stated, always contains a portion of this gas in a free state, a.^d 
although the quantity is small, it is sufficient to sustain the lives 
of its inhabitants. That fish, frogs, and other animals of tnis 
kind, cannot sustain life without oxygen gas, is proved by the 
fact, that they die in a short time, if the water in which they 
are placed is covered with a film of oil, so that no oxygen is 
admitted. Frogs, though capable of suspending their respira- 
tion for a long time, die in less than an hour, if the small 
quantity of water m which they are confined is covered with 
oil. Aquatic insects and worms exhibit the same phenome- 
na when treated in the same manner. In these cases, ex- 
periment has shown that oxygen is converted into carbonic 
acid, the efTect being the same as that produced by the re- 
spiration of v/arm blooded animals. 

Indeed, the experiments of Spallanzani prove that ani- 
mals produce this change by the action of their skin. Thus, 
serpents, lizards, and frogs, during their torpid state, and 
when their respiration is suspended, still require small por- 
tions of oxygen, which they constantly convert into carbonic 
acid by means of their skin, and it is probable, that in this 
manner, the blood of these animals parts with a little car 
bon. 

Animal Heat. 

During combustion there is an absorption of oxygen, and 
% suDsequent emission of carbonic acid gas, and in the act of 
respiration, oxygen disappears, and is replaced by the same 
acid gas. Combustion and respiration are therefore sup- 
ported by the same principle, and yield the same product. 

This analogy led Dr. Black to conclude that the changes 
which take place on the air, and on the blood in the lungs, 
was the cause of animal temperature ; and several circum- 
stances relative to the structure of animals and the quantity 
of oxygen they consume by respiration, seem to show that 
the heat of their blood depends, in a measure at least, on the 
quantity of this principle thus consumed. Animals having 
the power to maintain their temperatures above the media 
m which they live, are provided with capacious lungs, and 
consume large quantities of oxygen. Birds, the temperature 



How is it proved that fish and frogs require oxygen 7 What effect does the skin of Kw 
pid animals have upon oxygen 7 What analogy is there between combustion and respi- 
-ation'? What is said concernin? the quantity of oxygen caiisfi^me<l by warm blooded anS 
'Tials 7 



AXniAL HEAT. O^i'J 

of whose blood is higher than that of man, and quadrupeds, 
have lungs still more capacious, according to their size, and 
r.onsequemly, most probably consume more vital air. On 
the contrary, fish, frogs, and other animal of this tribe, 
which consume only very minute portions of oxygen, do not, 
sustain their temperature above the media in which they 
live. 

It appears also, that the temperature of an animal, when 
made to respire pure oxygen gas, is raised above the natural 
standard, but when the quantity of this gas consumed is 
small, the temperature of the animal falls, and the circula- 
tion of the blood is sluggish and languid. 

From these considerations, it would appear that the heat 
of the animal is sustained by its respiration, and that its 
temperature is proportionate, in some degree, to the quantity 
of oxygen it consumes, or converts into carbonic acid. 

Dr. Crawford, pursuing this idea, supposed that the car- 
bonic acid discharged by the breath, being generated in the 
lungs, and accompanied with the loss of oxygen, extricated 
heat daring its formation, and that the temperature of the 
animal might thus be explained. But as the heat of the 
lungs was found to be no greater than that of other internal 
parts, there must be some mode of accounting for its dis- 
tribution to other parts of the system, otherwise this 
.heory could not for a moment be supported. It is ob- 
vious that, in whatever manner this distribution is effected, 
the heat must be latent, or insensible; for supposing it to be 
in a free state, the lungs, or part where it is generated, 
would still be at a higher temperature than the parts to 
which it is distributed. 

Accordingly, on comparing the capacities of venous and 
arterial blood for heat, Dr. Craw^ford found, that arterial 
blood had the greatest capacity, and therefore, that at the 
same temperature, it contained a quantity of latent heat, 
which the venous blood did not. He therefore supposed 
that this latent heat was conveyed by the arterial blood, to 
all parts of the system, and as the arterial is gradually con- 
verted into venous blood, so the latent heat gradually be- 



What is said of the quanlity of oxygen consumed by fish and frogs 1 Does it appear 
that there is any proportion between the heat of the animal and the quantity of oxygen 
ttconsumes by respiration 1 How did Dr. Crawford explain the cause of animal temper- 
ature I Suppose arterial blood to >iave a greater capacity for heal than venous blood, on 
what circumstance could animal temperature be explained ^ 
28* 



^'^O ANIMAL HEAT. 

came sensible, in al! parts of the system, and that in this 
manner, animal ten p'jrature is maintained. 

This beautiful th eory was supposed to be founded on the 
true principles of chemistry and physiology, and being so 
received, it accounts very satisfactorily for animal tempera 
ture. But Dr. Davy has since shown that the principal fact 
on which it is founded, the difference of the capacities of ve- 
nous and arterial blood for heat, is not true, but that in this 
respect there is little or no difference between the two kinds 
of blood. 

If Dr. Davy has maintained the truth, it is obvious that Dr. 
Crawford's theory must fall to the ground. 

Although the facts stated above, in respect to the capacity 
of the lungs, in Avarm blooded animals, and the quantity of 
oxygen which they consume, when compared with cold 
blooded anim.als, would seem to show almost beyond a doubt, 
that animal temperature is connected with the quantity ol 
oxygen consumed, and the changes which the blood under- 
goes in the lungs ; still some physiologists deny the agency 
of either of these causes in producing such effects, and as- 
cribe the evolution of animal heat entirely to the influence oi 
the nervous system. 

The foundation of this doctrine, is an experiment of Mr 
Brodie, who found that on keeping up an artificial respira- 
tion in the lungs of a decapitated animal, the colour of the 
blood was changed from purple to red, and carbonic acid emii- 
ted as usual ; but that this animal grew cold more rapidly than 
another decapitated animal of the same kind which lay un- 
touched. It is obvious that this result would follow unless 
heat was evolved by the artificial respiration, because the 
air forced into the lungs would abstract the heat of the ani- 
mal. 

"Were these experiments rigidly exact, says Dr. Turner, 
they would lead to the opinion that no caloric is evolved by 
the mere process of arteriaiization. This inference cannot, 
however, be admitted, for two reasons : — First, because 
other physiologists, in repeating the experiments of Brodie, 
have found that the pn^cess of cooling is retarded by artifi- 



How did Dr. Da 7 show that Dr Crawford's theory was untenable 1 What is the foun 
dation of ilie theo '/ that ani'.-sTial h iat is cvoivcd hy the nervous system 1 If heat were 
not evolved by artificial respirati n, why should this process cool the animal rapidly 1 
What are Ur. Turner's two reasor for supposing that Mw Brodie's experiments are noi 
conciusivcj that lieai is not e vol vet by reppiratlon 7 



ANIMAL HEAT. 331 

cKxl respiration ; and, secondly, because it is difficult tc coj?)- 
ceive why the formation of carbonic acid, which unifornJy 
gives rise to increase of temperature in other cases, should 
not be attended within the animal body with similar results. 
It may hence be inferred, that this is one of the sources of 
animal heat." 

In respect to the influence of the nervous system over the 
development of animal temperature, there is no doubt but 
considerable effects may be safely attributed to this cause. 
But in what manner the heat is evolved, is perhaps uncer- 
tain. 

In conclusion, we may remark, that the subject of animal 
temperature has excited the attention, and has been made an 
object of experiment and research among philosophers and 
physiologists in all ages, and that many ingenious and some 
plausible theories have been invented and detailed, in order 
to give satisfactory explanation of its cause. The theory 
of Dr. Crawford, among these, was perhaps the most plausi- 
ble, and certainly the most philosophical and beautiful. But 
we have seen, that the leading facts on which it was found- 
ed, have been proved by his successors not to be true, and 
therefore the theory itself cannot be maintainea. That the 
oxygen of the atmosphere is one of the causes of animal heat 
cannot be doubted, from the facts, that no animal can live 
without it, and that the heat of animals is in some propor- 
tion to the quantity of this principle consumed. 

But as this principle can have no effect, except through 
the lungs, if it is admitted that heat is evolved by its action 
there, there is still much difficulty in explaining either why 
the lungs are not constantly at a higher temperature than the 
other parts of the system, or if they were, how the heat could 
be conveyed to the other parts, from its fountain. 

On the whole, it appears that the cause of animal heat is 
one of the arcana of nature, into which man has not yet been 
permitted to look, and therefore, we must be contented al 
present to attribute it to the vital principle. 



Is it probab'e that the nerves affect thp, tempeiature of the animal % What is said in 
conclusion on mis subject 7 Has there beeri aa/ theory proposed whicli accounts satis- 
factorily for the cause of animal heat 7 f o what is it said must we a. yt^ni aitribute the 
cause of aninrallieat 1 



332 ANALYSIS OF GASES 

PART IV. 

ANALYTICAL CHEMISTRY. 

To enter into a detailed account of experimental and ana 
rytical chemistry, is altogether inconsistent with the design 
and limits of the present work. My sole object in this de 
partment is to give a few concise directions for conducting 
some of the more common analytical processes ; and in or 
der to render them more generally useful, I shall give exam 
pies of the analysis of mixed gases, of minerals, and of mine 
ral waters. 



ANALYSIS OF MIXED GASES. 

Analysis of air, or of gaseous mixtures containing oxygen 
Of the various processes by which oxygen gas may be with 
drawn from gaseous mixtures, and its quantity determined, 
none are so convenient and precise as the method by means 
of hydrogen gas. In performing this analysis, a portion ol 
atmospheric air is carefully measured in a graduated tube, 
and mixed with a quantity of hydrogen, which is rather more 
than sufficient for uniting with all the oxygen present. The 
mixture is men introduced into a strong glass tube called Vol- 
ta's eudiometer, and is inflamed by the electric spark, the 
aperture of the tube being closed by the thumb at the mo- 
ment of detonation. The total diminution in volume, divided 
by three, indicates the quantity of oxygen originally contain 
ed in the mixture. This operation may be performed in a 
trough either of water or mercury. 

Instead of electricity, spongy platinum (page 126) may be 
employed for causing the union of oxygen and hydrogen 
gases ; and, while its indications are very precise, it has the 
advantage of producing the effect gradually and without de- 
tonation. The most convenient mode of employing it Avith 
*his intention is the following. A mixutre of spongy plati- 
num and pipe-clay, in the proportion of about three parts of 
the former to one of the latter, is made into a paste with *; 
water, and then rolled between the fingers into a globular 
form. In order to preserve the spongy texture of the plati- 
num, a little muriate of ammonia is mixed with the paste ; and 
^hen the ball has become dry, it is cautiously ignited at the 
flame of a spirit-lamp. The sal-ammoniac, escaping from 
all parts of the mass, gives it a degree of porosity which is 
peculiarly favorable to its action. The ball, thus preparea, 
should be protected from dust, and be heated to redness just 



ANALYSIS OF GASE^. 333 

I'^fyre being used. To insure accuracy, the hydrogen em- 
jibyed should be kept over mercury for a few hours in con- 
tact with a spongy platinumball and a piece of caustic pot- 
ash. The first deprives it of traces of oxygen which it 
commonly contains, and the second of moisture and sulphu- 
retted hydrogen. The analysis must be performed in a mer- 
curial trough. The time required for completely removing 
the oxygen depends on the diameter of the tube. If the 
mixture is contained in a very narrow, tube, the diminution 
does not arrive at its full extent in less than twenty minutes 
or half an hour ; while in a vessel of an inch in diameter 
ihe effect is complete in the course of G.ve minutes. 

Mode of determining the quantity of nitrogen in gaseous 
mixtures. — As atmospheric air, which has been deprived of 
moisture and carbonic acid, consists of oxygen and nitrogen 
only, the proportion of the latter is of course known as soon 
as that of the former is determined. The only method, in- 
deed, by Avhich chemists are enabled to estimate the quantity 
of this gas, is by withdrawing the other gaseous substances 
Nvith which the nitrogen is mixed. 

Mod.e of determining the qua^ntity of carbonic acid in gaseous 
mixtures. — When carbonic acid is the only acid gas which 
is present, as happens in amospheric air, in the ultimate 
analysis of organic compounds, and in most other analogous 
researches, the process for determining the quantity of car- 
bonic acid is exceedingly simple ; for it consists merely in 
absorbing that gas by lime water or a solution of caustic po- 
tash. This is easily done in the course of a few minutes in 
an ordinary graduated tube; or it may be effected almost in- 
stantaneously by agitating the gaseous mixture with the alka- 
line solution in Hope's eudiometer. This apparatus is form- 
ed of two parts ; a bottle capable of containing about twenty 
drachms of fluid, and furnished with a well-ground stopper ; 
and a tube of the capacity of one cubic inch, divided into 
iOO equal parts, and accurately fitted by grinding to the neck 
of the bottle. The tube, full of gas, is fixed into the bottle 
previously filled with lime water, and its contents r.re briskly 
agitated. The stopper is then withdrawn under water, when 
a portion of liquid rushes into the tube, supplying the place 
of the gas which has disappeared ; and the process is after- 
wards repeated, as long as any absorption ensues. 

The eudiometer of Dr. Hope was originally designed for 
analyzing air or other similar mixtures, the bottle being Q^^d 



334 ANALYSIS OF GASES. 

with a solution. of the hydro-sulphuret of potassa or lime, or 
some liquid capable of absorbing oxygen. To tiic^ employ- 
ment of this apparatus it has been objected, that ihc absorp- 
tion is rendered slow by the partial vacuum which 13 continu- 
ally taking place within it, an inconvenience particularly felt 
towards the close of the process, in consequence of the eudi- 
ometric liquor being diluted by the admission of water. To 
remedy this defect, Dr. Henry has substituted a bottle of elas- 
tic gum for that of glass, by which contrivance no vacuum 
can occur. From the improved method of analyzing air, 
however, this instrument is now rarely employed in eudiome- 
try ; but it may be used with advantage for absorbing carbo- 
nic acid of similar gases, and is particularly useful for the 
purpose of demonstration. 

Mode of analyzing mixtures of hydrogen and other injiam- 
mahle gases. — When hydrogen is mixed with nitrogen, air, or 
other similar gaseous mixtures, its quantity is easily ascer- 
tained by causing it to combine with oxygen either by means 
of platinum sponge or the electric spark. If, instead of hy- 
drogen, any other combustible substance, such as carbonic 
oxide, light carburetted hydrogen, or olefiant gas, is mixed 
with nitrogen, the analysis is easily affected by adding a suf- 
ficient quantity of oxygen, and detonating the mixture by 
electricity. The diminution in volume indicates the quantity 
of hydrogen contained in the gas, and from the carbonic acid, 
which may then be removed by an alkali, the quantity of car- 
bon is inferred. 

When olefiant gas is mixed with other inflammable gases, 
its quantity is easily determined by an elegant and simple 
process proposed by Dr. Henry. It consists in mixing 100 
measures, or any convenient quantity of the g?iseous mixture, 
with an equal volume of chlorine in a vessel covered with a 
piece of cloth or paper, so as to protect it from light ; and 
after an interval of about ten minutes, the excess of chlorine 
is removed by lime water or potassa. The loss experienced 
by the gas to be analyzed, indicates the exact quantity of ole- 
fiant gas which it had contained. 

In mixtures of hydrogen, carburetted hydrogen, and car- 
bonic oxide, the analytic process is exceedingly^ difiicult and 
complicated, and requires all the resources of the most re- 
fined chemical knowledge, and all the address of an experi- 
enced analyst. The most recent information on this subject 
will be found in Dr. Henry's Essay in the Philosophical 
Transactions for 1824. 



ANALYSIS OF MINERALS. 335 

ANALYSIS OF MINERALS. 

As the very extensive nature of this dep'ann?en^ of analj^ti- 
cal chemistry renders a selection necessary, i sh^Jl confine 
my lemarks solely to the analysis of those earthy minerals 
with which the beginner usually commences his labours. The 
most common constituents of these compounds are silica, alu- 
mina, iron, manganese, lime, magnesia, potassa, soda, and 
the carbonic and sulphuric acids ; and I shall, therefore, en- 
deavor to give short directions for determining the quantity of 
each of these substances. 

In attempting to separate two or more fixed principles from 
each other, the first object of the analytical chemist is to 
bring them into a state of solution. If they are solubl'3 in 
water, this fluid is preferred to every other menstruumi, but 
if not, an acid or any convenient solvent may be employed. 
In many instances, however, the substance to be analyzed 
resists the action even of the acids, and in that case, the fol- 
lowing method is adopted : — The compound is first crushed, 
by means of a hammer, or a steel mortar, and is afterwards 
reduced to an impalpable powder in a mortar of agate ; it is 
then intimately mixed with three, four, or more times its 
weight of potassa, soda, baryta, or their carbonates ; and last- 
ly, the mixture is exposed in a crucible of silver or platinum 
to a strong heat. During the operation, the alkali combines 
with one or more of the constituents of the mineral ; and, 
consequently, its elements being disunited, it no longer resists 
the action of the acids. 

Analysis of Marble or CarhonoAe of Lime. — This analysis 
is easily made by exposing a known quantity of marble, for 
i about half an hour, to a full white heat by Avhich means the 
\ carbonic acid gas is entirely expelled, so that by the loss in 
ii Wt;ight the quantity of each ingredient, supposing the marble 
;!to have been pure, is at once determined. In order to as- 
I certain that the whole loss is owing to the escape of carbonic 
'acid, the quality of this gas may be determined by a compa- 
rative analysis. Into a small flask, contain'hig muriatic acid, 
diluted with two or three parts of water, a known quantity o. 
marble is gradually added, the flask being inclined to one 
side in order to prevent the fluid from being flung out of the 
I vessel during the effervescence. The diminution in weiglU 
.experienced by the flask and its contents, indicates the qu.3n.= 
[city of carbonic acid which has been expelled. 

Should the carbonate suflTer a greater loss in the fire tha^ 



336 ANALYSIS or MINERALS. 

when decomposed by an acid, it will most p'" ''jably b? found 
to contain water. This may be ascertained by heating a 
piece of it to redness, m a glass tube, the sides of which will 
be bedewed with moisture, if water is present. Its quantity 
may be determined by causing the watery vapour to pass 
through a weighed tube filled with fragments of the chloride 
of calcium, (muriate of lime,) by which the moisture is ab- 
sorbed. 

Separation of Lime and Magnesia.- — The more common 
kinds of carbonate of lime frequently contain traces of sili- 
cious and aluminous earths, in consequence of which, they 
are not completely dissolved in dilute muriatic acid. A very 
frequent source of impurity is the carbonate of magnesia^ 
which is often present in such quantity ihat it forms a pecu* 
liar compound called magnesian limestone. The analysis of 
this substance, so far as respects carbonic acid, is the same as 
that of marble. The separation of the two earths may be con- 
veniently effected in the following manner. The solution of 
the mineral in muriatic acid is evaporated to perfect dryness^ 
in a fiat dish or capsule of porcelain, and after re-dissolving 
the residuum, in a moderate quantit}?- of distilled water, a solu- 
tion of the oxalate of ammonia is added as long as a precipi- 
tate ensues. The oxalate of lime is then allowed to subside, 
collected on a filter, converted into quicklime by a white heat, 
and weighed ; or the oxalate may be decomposed by a red 
heat, the carbonate resolved into the sulphate of lime by sul- 
phuric acid, and the excess of acid expelled by a tempera- 
ture of ignition. To the filtered liquid containing the mag- 
nesia, an excess of carbonate of ammonia^ and then phos- 
phate of soda is added, when the magnesia in the form of the 
ammoniaco-phosphate is precipitated. Of this precipitate 
heated to redness, 100 parts correspond to 40 of pure mag- 
nesia. (Murray.) 

Earthy Sulphates. — The mo5t abundant of the earthy sul 
phates, is that of lime. The analysis of this compound i? 
easily efTected. By boiling it for fifteen or twenty minutes 
with a solution of twice its weight of the carbonate of soda^! 
double decom_position ensues: and the carbonate of lime 
after being collected on a filter and washed with hot water, i; 
either heated to low redness, to expel the water, and Aveighed 
or at once reduced to quicklime by a Vv^hite heat. Of the di i 
carbonate, fifty parts correspond to twenty-eight of liiiic 
The alkaline solution is acidulated with muriatic acid, anc 
the sulphuric acid thrown Ao\y\-\ by the muriate cf baryta 



ANALYSIS OF MINERALS. 337 

from the sulphate of this earth, collected and dried at a red 
heat, the quantity of acid may easily be estimated. 

The method of analyzing the sulphates of strontia and ba- 
ryta is somewhat different. As these salts are difficult of de- 
composition in the moist way, the following process is adopt- 
ed. The sulphate, in fine powder, is mixed with three times 
its weight of the carbonate of soda, and the mixture is heat- 
ed to redness in a platina crucible, for the space of half an 
hour. The ignited mass is then digested in hot water, and 
the insoluble earthy carbonate collected on a filter. The oth- 
er parts of the process are the same as the foregoing. 

Mode of analyzing compounds of Silica, Alumina, and Iron. 
Minerals, thus constituted, are decomnosed by an alkaline 
carbonate, potash, or soda, at a red heat, in the same manner 
ds the sulphate of baryta. The mixture is afterwards digest- 
ed in dilute muriatic acid, by which means all the ingredi- 
ents of the mineral, if the decomposition is complete, are 
dissolved. The solution is next evaporated to dryness, the 
heat being carefully regulated towards the close of the pro- 
cess, in order to prevent any of the chloride of iron, the vol- 
atility of which is considerable, from being dissipated in va- 
por. By this operation, the silica, though previously held in 
solution by the acid, is entirely deprived of its solubility ; so 
ihat on digesting the dry mass in water, acidulated with mu- 
riatic acid, the alumina and iron are taken up, and the silica 
is left in a state of purity. The siliceous earth, after sub- 
siding, is collected on a filter, carefully edulcorated, heated 
eo redness, and weighed. 

To the clear liquid containing iron and alumina, a consid- 
erable excess of a solution of pure potassa is added ; so as 
not only to throw down these oxides, but to dissolve the alu- 
mina. The peroxide of iron is then collected on a filter, edul- 
corated carefully until the washings cease to have an alkaline 
reaction, and is well dried on a sand bath. Of this hydrated 
peroxide, forty-nine parts contain forty of the anhydrous pe- 
roxide of iron. But the most accurate mode of determining 
} its quantity is by expelling the water by a red heat. This op- 
; eration, however, should be done with care ; since any ad- 
I tiering particles of paper, or other combustible matter, w^ould 
i bring the iron into the state of black oxide, a change which 
I IS known to have occurred by the iron being attracted by a 
I magnet. 

I To procure the alumina, the liquid in which it is dissolved 
I ts boiled vvith sal-ammoniac, when the muriatic acid unites 
29 



333 ANALYSIS OF MINERALS. 

with the potassa, the volatile alkali is dissipated in vapor, and 
the alumina subsides. As soon as the solution is thus render- 
ed neutral, the hydrous alumina is collected on a filter, dried 
by exposure to a white heat, and quickly weighed after remo- 
val from the fire. 

Separation of Iron and Manganese. — A compound of these 
metals or their oxide may be dissolved in muriatic acid. I; 
the iron is in a large proportion compared with the manga 
nese, the following process may be adopted with advantage 
To the cold solution, considerably diluted \TOh water, anc 
acidulated with muriatic acid, carbonate of soda is gradually 
added, and the liquid is briskly stirred ^^-ith a glass rod, during 
the effervescence, in order that it may become highly charofec 
with carbonic acid. By neutralizing the solution in thif 
manner, it at length attains a point at which the peroxide o 
iron is entirely deposited, leaving the liquid colourless : whiL 
the manganese, by aid of the free carbonic acid, is kept ii 
solution. The iron, after subsiding, is collected on a riltei 
and its quantity determined in the usual manner. The filtei 
ed liquid is then boiled with an excess of the carbonate o 
soda ; and the precipitated carbonate of manganese is col 
lected, heated to low redness in an open crucible, by which i 
is converted into the bro^\-n oxide, and weighed. This metfc 
od is one of some delicacy ; but in skilfiil hands, it affords 
very accurate result. It may also be employed for separatir 
iron from magnesia and lime as well as from manganese. 

But if the proportion of iron is small, compared with that ( 
manganese, the best mode of separating it is by the succ 
nate of ammonia or soda, prepared by neutralizing a sohitio 
of sue cine acid with either of those alkalies. That this pre 
cess should succeed, it is necessary that the iron be wholl 
in the state of peroxide, that the solution be exactly neutra 
which may easily be insured, by the cautious use of amm( 
nia, and that the reddish-bro^^m coloured succinate of iron I 
washed with cold water. Of this succinate, well dried at 
temperature of 212'' F., 90 parts correspond to 40 of the pe: 
oxide. From the filtered liquid, the manganese may be pr« 
cipitated at a boiling temperature by carbonate of soda, an 
its quantity determined in the way above mentioned. Tt 
benzoate may be substituted for the succinate of ammonia i 
the preceding process. 

It may be stated as a general rule, that whenever it is ii 
.ended to precipitate iron by means of the alkalies, the succ 
nates, or benzoates, it is essential that this metal be hi tl 



ANALYSIS OF MINERALS. 339 

inaximum of oxidation. It is easily brought into this state by 
digestion with a little nitric acid. 

Separation of manganese from lime and magnesia. — K the 
quantity of the former be proportionally smaU, it is precipita- 
ted as a sulphuret by the hydrosulphuret of ammonia or pot- 
assa. This sulphuret is then dissolved in muriatic acid, and 
the manganese thrown down as usual by means of an alkali. 
But if the manganese be the chief ingredient, the best method 
is to precipitate it at once, together with the two earths, by a 
fixed alkaline carbonate at a boiling temperature. The pre- 
cipitate, after being exposed to a low red heat and weighed, 
is put into cold water, acidulated with a drop or rwo of nitric 
acid, when the lime and magnesia will be slowly dissolved 
with effervescence. Should a trace of the manganese be 
like^^-ise taken up, it may easily be thrown down by the hy- 
drosulphuret of ammonia. 

Mode of analyzing an earthy mineral containing silica, iron, 
alumina, manganese, lime and magnesia. — The mineral, re* 
duced to a fine powder, is ignited with three or four times its 
weight of the carbonate of potassa or soda, the mass is taken 
up in dilute muriatic acid, and the silica separated in the way 
already described. To the solution, thus freed from silica 
and duly acidulated, carbonate of soda is gradually added, so 
as to charge the liquid with carbonic acid, as in the analysis 
of iron and manganese. In this manner the iron and alumina 
are alone precipitated, substances which may be separated 
from each other by means of pure potassa. The manganese, 
lime, and magnesia, may be determined by the processes al- 
ready described. 

Analysis 9f minerals containing a fixed alkali. — When the 
object is to determine the quantity of a fixed alkali, such as pot- 
assa or soda, it is necessary to abstain from the emplo^Tuent 
of these reagents in the analysis itself; and the beginner will 
do well to devote his attention to the alkaline ingredients 
only. On this supposition, he will proceed in the following 
manner. The mineral is reduced to a very fine powder, mixed 
intimately T\'ith six times its weight of the artificial carbonate 
of bar^na and exposed for an hour to a white heat. The 
ignited mass is dissolved in dilute muriatic acid, and the so- 
lution evaporated to perfect drjTiess. The soluble parts are 
laken up in hot water : an excess of the carbonate of ammo- 
nia is added : and the insoluble matters, consisting of silica, 
carbonate of baryta, and all the constituents of the mineral, 
excepting the fixed alkali, are collected on a filter. Th« 



340 ANALYSIS OF MINERALS. 

clear solution is evaporated to dryness in a porcelain capsule, 
and the dry mass is heated to redness in a crucible of plati- 
niim, in order to expel the salts of ammonia. The residue is 
the chloride of potassium or sodium. 

In this analysis, it generally happens that traces of manga- 
nese, and sometimes of iron, escape precipitation in the first 
part of the process ; and, in that case, they should be thrown 
down by the hydrosulphuret of ammonia. If neither limo 
nor magnesia is present, the alumina, iron, and manganese, 
may be separated by pure ammonia, and the baryta subse- 
quently removed by the carbonate of that alkali. By this 
method the carbonate of baryta is recovered in a pure state, 
and may be reserved for another analysis. The baryta may 
also be thrown doAvn as a sulphate by sulphuric acid, in which 
case, the soda or potassa is procured in combination with that 
acid. 

The analysis is attended with considerable inconvenience, 
when magnesia happens to be present, because this earth is 
not completely precipitated, either by ammonia or its carbo- 
nate ; and, therefore, some of it remains with the fixed alkali. 
The best mode with which I am acquainted for effecting its 
separation, is the following. The carbonate of ammonia is 
first added, and the phosphoric acid is dropped into the liquid, 
until all the magnesia is thrown down in the form of the am- 
moniaco-magnesian phosphate. The excess of phosphoric 
acid is afterwards removed by the acetate of lead, and thai 
of lead by sulphuretted hydrogen. The acetate of the alkali 
is then brought to dryness, ignited, and by the addition of sul- 
phate of ammonia is converted into a sulphate. 

In the preceding account, several operations have been al- 
luded to, which, from their importance, deserve more particu- 
lar mention. The process of filtering, for example, is one on 
which the success of analysis materially depends. Filtration 
is effected by means of a glass funnel, into which a filter, made 
of white bibulous paper, is inserted. For researches of deli- 
cacy, the filter, before being used, is macerated for a day or 
two in water, acidulated with nitric acid, in order to dissolve 
iime and other substances contained in common paper, and it 
is afterwards washed with hot water, till every trace of acid 
is removed. It is next dried at 212°, or any fixed temperature 
insufficient to decompose it, and then carefully weighed, tho 
weight being marked upon it with a pencil. As dry paper 
absorbs hygrometic moisture rapidly from the atmosphere, 
the filter, while being weighed, should be inclosed in a light 



ANALYSIS OF MINERAL WATERS. 341 

Dox made for the purpose. When a precipitate is collected 
on a fiher, it is washed with pure water until every trace of 
the original liquid is removed. It is subsequently dried and 
weighed as before, and the weight of the paper subtracted 
from the combined weight of the filter and precipitate. The 
trouble of weighing the filter may sometimes be dispensed 
with. Some substances, such as silica, alumina, and lime, 
which are not decomposed when heated with combustible 
matter, may be put into a crucible while yet contained in the 
filter, the paper being set on fire before it is placed in the 
[furnace. In these instances, the ash from the paper, tht 
i average weight of which is determined by previous experi- 
ments, must be subtracted from the weight of the heated 
mass. 

The tests commonly employed in ascertaining the acidity 
or alkalinity of liquids are litmus and turmeric paper. The 
former is made by digesting litmus, reduced to a fine powder, 
in a small quantity of water, and painting with it white paper 
. which is free from alum. The turmeric paper is made in a 
similar manner ; but the most convenient test of alkalinity is 
litmus paper reddened by a dilute acid. 

ANALYSIS OF MINERAL WATERS. 

Rain water collected in clean vessels in the country, or 

, freshly fallen snow, when melted, affords the purest kind of 

I water which can be procured without having recourse to dis- 

1 tillation. The water obtained from these sources, however, 

jis not absolutely pure, but contains a portion of carbonic acid 

: and air, absorbed from the atmosphere. It is remarkable 

1 that this air is very rich in oxygen. That procured from 

i snow-water by boiling, was found by Gay Lussac and Hum- 

\ boldt to contain 34.8 and that from rain water 32 per cent, of 

I oxygen gas. From the powerfully solvent properties of 

; water, this fluid no sooner reaches the ground and percolates 

through the soil, than it dissolves som.e of the substances 

which it meets with in its passage. Under common circunv 

stances, it takes up so small a portion of foreign matter that 

I Its sensible properties are not materially affected, and in this 

' state it gives rise to spring, well, and river water. Sometimes, 

on the contrary, it becomes so strongly impregnated with 

saline and other substances, that it acquires a peculiar flavor, 

and is thus rendered unfit for domestic uses. It is then known 

by the name of mineral water. 

29* 



542 ANALYSIS OF MINERAL WATERS. 

The composition of spring water is dependent on. the nature 
of the soil through which it flows. If it has filtered through 
primitive strata, such as quartz rock, granite, and the like, ii 
is in general very pure ; but if it meets wdth limestone or gyp- 
sum in its passage, a portion of these salts is dissolved, and 
communicates the property called hardness. Hard water is 
characterized by decomposing soap, the lime of the former 
yielding an insoluble compound wdth the oil of the latter If 
this defect is owing to the presence of the carbonate of lime, 
it is easily remedied by boiling, when free carbonic acid is 
expelled, and the insoluble carbonic of lime subsides. If 
sulphate of lime is present, the addition of a little carbonate 
of soda, by precipitating the lime, converts the hard into soft 
water. Besides these ingredients, the muriates of lime and 
soda are frequently contained in spring w^ater. 

Spring water in consequence of its saline impregnation, is 
frequently unfit for chemical purposes, and on these occasions 
distilled Avater is employed. Distillation may be performed 
on a small scale by means of a retort, in the body of w^hich 
water is made to boil, while the condensed vapor is received 
in. a glass flask, called a recipient, which is adapted to its beak 
or open extremity. This process is more conveniently con- 
ducted, however, by means of a still. 

The different kinds of mineral water may be conveniently 
arranged for the purpose of description in the four divisions 
of carbonated, chalybeate, sulphurous, and saline springs. 

The carbonated springs of which those of Seltzer, Spa, 
Pyrmont, Baliston and Carsbad, are the m.ost celebrated, are 
distinguished by containing a considerable quantity of free 
carbonic acid, owing to the escape of which they sparkle 
when poured from one vessel into another. They commu- 
cate a red tint to litmus paper before, but not after being 
boiled, and the redness disappears on exposure to the air. 
Mixed with a sufficient quantity of lime water, they become 
turbid from the deposition of carbonate of lime. They fre- 
quently contain the carbonate of lime, magnesia, and iron, in 
consequence of the facility with which these salts are dissolv- 
ed by water charged with carbonic acid. 

The best mode of determining the quantity of carbonic acid 
is by heating a portion of the water in a flask, and receivin 
the carbonic acid by means of a bent tube, in a graduated jai 
filled with mercury. 

The chalybeate vraters are characterized by a strong styp 
Vi^ inky taste, and by striking a black colour with the infu 







ANALYSIS OF MINERAL WATERS. 343 

sion of Gallnuts. The iron is sometimes combined with the 
muriatic or sulphuric acid ; but most frequently it is in the 
form of a carbonate of the protoxide, held in solution by free 
carbonic acid. On exposure to the air, the protoxide is oxi- 
dized, and the hydrated peroxide subsides, causing the ochre- 
ous deposit, so commonly observed in the vicinity of chaly 
beate springs. 

To ascertain the quantity of iron contained in a mineral 
water, a known w^eight of it is concentrated by evaporation, 
and the iron brought to the state of peroxide by means of ni- 
tric acid. The peroxide is then precipitated by an alkali and 
weighed ; and if lime and magnesia are present, it may be 
separated from those earths by the process described in the 
last section. 

Chalybeate waters are by no means uncommon ; but the 
most noted in Britain are those of Tunbridge, Cheltenham, 
and Brighton. The Bath w^ater also contains a small quan- 
tity of iron. 

The sulphurous waters, of which the springs of Aix la Cha- 
peile, Harrowgate, and Moffat afford examples, contain sul- 
phuretted hydrogen, and are easily recognized by their odor, 
and by causing a browTi precipitate with a salt of lead or sil- 
ver. The gas is readily expelled by boiling, and its quantity 
may be inferred by transmitting it through a solution of the 
acetate of lead, and weighing the sulphuret which is gene- 
rated. 

Those mineral springs are called saline which do not be- 
long to either of the preceding divisions. The salts which 
are most frequently contained in these waters, are the sul- 
phates, muriates, and corbonates of lime, magnesia, and soda. 
Potassa sometimes exists in them, and Berzelius has found 
lithia in the spring at Carlsbad. It has lately been discovered 
that the presence of hydriodic acid in small quantity is not 
unfrequent. As examples of saline water may be enumera- 
ted the springs of Epsom, Chehenham, Bath, Bristol, Bareges, 
Buxton, Pitcaithly, Toeplitz, Ballston, and Saratoga. 

The first object in examining a saline spring is to determine 
the nature of its ingredients. Muriatic acid is detected by 
the nitrate of silver, and the sulphuric acid by muriate oi 
baryta ; and if an alkaline carbonate be present, the precipi- 
tate occasioned by either of these tests will contain a carbon- 
ate of silver or barjrta. The presence of lime and magnesia 
may be discovered, the former by the oxylate of lime, and the 
latter by carbonate of ammonia and phosphoric acid. Po- 



344 ANALYSIS OF MINERAL WATERS. 

tassa is known by the action of the muriate of platinum. T^ 
detect soda, the water should be evaporated to dryness, the 
deliquescent salts removed by alcohol, and the matter insolu- 
ble in that menstruum taken up by a small quantity of water, 
and be allowed to crystallize by spontaneous evaporation. 
The salt of soda may then be recognized by the rich yellow 
colour which it communicates to flame. If the presence of 
hydriodic acid is suspected, the solution is brought to dry- 
ness, the soluble parts dissolved in two or three drachms of 
a cold solution of starch, and strong sulphuric acid gradually 
added. 

Having thus ascertained the nature of the saline ingredi- 
ents, their quantity may be determined by evaporating a pint 
of water to dryness, heating to low redness, and weighing 
the residue. In order to make an exact analysis, a given 
quantity of the mineral water is concentrated in an evapora- 
ting basin as far as can be done without causing either pre- 
cipitation or crystallization, and the residual liquid is divided 
into two equal parts. From one portion the sulphuric and 
carbonic acids are thrown down by the nitrate of baryta, 
and after collecting the precipitate on a filter, the muriatic 
acid is precipitated by the nitrate of silver. The mixed sul- 
phate and carbonate is exposed to a low red heat, and weigh- 
ed ; and the latter is then dissolved by dilute muriatic acid, 
and its quantity determined by weighing the sulphate. The 
chloride of silver, of which 146 parts correspond to 37 of 
muriatic acid, is fused in a platinum spoon or crucible, in 
order to render it quite free from moisture. To the other 
half of the concentrated mineral water, oxalate of lime is ad- 
ded for the purpose of precipitating the lime ; and the magne- 
sia is afterwards thrown down as the ammoniaco-phosphate, 
by means of the carbonate of ammonia and phosphoric acid. 
Having thus determined the weight of each of the fixed in- 
gredients, excepting the soda, the loss of course gives the 
quantity of that alkali ; or it may be procured in a separate 
state by the process described in the foregoing section. 

The individual constituent of the water being knoAvn, if 
remains to determine the state in which they were originally 
combined. In a mineral water containing sulphuric and mu- 
riatic acids, lime, and soda, it is obvious that three cases are 
possible. The liquid may contain sulphate of lime and mu- 
riate of soda, muriate of lime and sulphate of soda, or each 
acid may be distributed between both the bases. It was at 
one time supposed that the lime must be in combination with 



ANALYSIS OF MINERAL WATERS. 845 

sulphuric acid, because the sulphate of that earth is left when 
the water is evaporated to dryness. This, however, by no 
means follows. In whatever state the lime may exist in the 
original spring, gypsum will be generated as soon as the con- 
centration reaches that degree at which sulphate of lime 
cannot be held in solution. The late Dr. Murray,* v^ho 
treated this question with much sagacity, observes, that some 
mineral waters, which contain the four principles above men- 
tioned, possess higher medicinal virtues than can be justly 
ascribed to the presence of sulphate of lime and muriate of 
soda. He advances the opinion, that alkaline bases are uni- 
ted in mineral waters with those acids with which they form 
the most soluble compounds, and that the insoluble salts ob- 
tained by evaporation are merely products. He therefore 
proposes to arrange the substances determined by analysis 
according to this supposition. To this practice there is no 
objection ; but it is probable that each acid is rather distri- 
buted between several bases, than combined exclusively with 
one of them. 

Sea water may be regarded as one of the saline mineral 
waters. Its taste is disagreeably bitter and saline, and its 
fixed constituents amount to about three per cent. Its spe- 
cific gravity varies from 1.0269 to 1.0285 ; and it freezes at 
about 28.5° F. According to the analysis of Dr. Murray, 
10,000 parts of water from the Firth of Forth contain 220.01 
parts of common salt, 33.16 of sulphate of soda, 42.08 of 
muriate of magnesia, and 7.84 of muriate of lime. Dr. 
Wollaston has detected potassa in sea water, and it likewise 
contains small quantities of the hydriodic and iodic and 
hydrobromic acids. 

The water of the Dead Sea has ,a far stronger saline im- 
pregnation than sea water, containing one fourth of its w^eight 
of solid matter. It has a peculiarly bitter, saline, and pun- 
gent taste, and its specific gravity is 1.211. According to 
the analysis of Dr. Marcet, 100 parts of it are composed of 
muriate of magnesia 10.246, muriate of soda 10.36, muriate 
of lime 3.92, and sulphate of lime 0.054. In the river Jor- 
dan, which flows into the Dead Sea, Dr. Marcet discovered 
the same principles as in the lake itself — Turner's Chemistry, 



' Philosophical Transactions of Edinburgh, vol. vii. 



34G CHEMICAL MIXEP.ALOGY. 



PART Y. 



CHEMICAL MINERALOGY. 



By Chemical Mineralogy, we mean the application of the 
principles of chemistry to the examination of mineral sub- 
stances. 

In this short treatise on the subject, we shall be confmed 
chiefly to the examination of the most common mineral 
bodies, and hope to give such plain directions as will ena- 
ble the student to assay the most important metalic ores 
of our country. 

Instruments and preparatory steps necessary for the 
analysis of mat alii c ores. — Before we proceed to show the 
methods by which ores are analysed, it will be necessary to 
describe a few simple instruments which are required for 
this purpose ; and also to point out what preliminary steps 
are necessary in order to prepare the ores for analysis. 

1. ABalance, or pair of small scales, in order to ascer- 
tain the weight of the ore to be examined. Also to take 
the specific gravities of minerals. The latter may be done 
by the method and instrument described at p. 107 of this 
volume. 

2. Blow-pipe. For a description of this, and the man- 
ner of using it, see p. 103. 

3. Supports. In order to use the blow-pipe, it is necessa- 
ry to employ a support, on which the substance to be heat- 
ed, rests. In ordinary cases, a piece of charcoal answers 
for this purpose, but in others it is necessary to use a small 
platina spoon, or piece of platina foil, instead of the char- 
coal. 

4. Magnet. This is used in order to ascertain whether 
the ore contains metallic iron. The best form is that of a 
small needle suspended on a fine point of copper, or brass. 
The ore should be tried both before and after being heated 
by the blow-pipe ; because, although the ore may contain 
iron it may not be magnetic until it is reduced. 

5. Mortar and Pestle. A common wedgewood mortar 
is sullicient for most purposes. All substances to be ana- 
lysed must be levigated as finely as possible. In most in- 
stances, the action of the solvents will be incomplete vrith- 
out this preparation. 



tirtEMtlCAL MlNEUALOGY. 347 

6. A Flaslc for digesting the ore after levigation, is ne- 
cessary. This has already been described at p. 102. 

7. Test Tubes, These are of glass, live or six inches 
long, and of various sizes. They may be made by taking 
pieces of glass tube, already broken, and closing them at 
one end by means of the blo\v-pip3, or alcohol lamp. They 
are employed to subject small portions of the clear filtered 
solution of any substance to the action of various tests, and 
are among^e indispensable instruments of analysis. 

8. Glas.x plates. In many instances, when the quantity 
of matter is small, a drop in solution, placed on a glass 
plate, and then the test applied by means of a point of glass, 
or piece of platina wire, will decide all the operator wishes 
to know before he proceeds to further trials. Where the 
solution contains neutral, or other salts, by allowing the 
dro}) to dry we may decide what the solution is, by the 
forms of the crystals on the glass. {For crystalline forms,, 
see the author's Mineralogy.) 

Prccesscs necessary hefore the chemical examination 
of metallic substances. 

Roasting. This consists in keeping the ore at a mode- 
rate heat for a considerable length of time, in order to drive 
off all the volatile matter it contains, as water, carbonic 
acid, sulphur, &c. Roasting in the large way is performed 
by placing alternate layers of the ore, and wood or coal, in 
a chimney erected for this purpose, and then setting the 
fuel on fire at the bottom of the pile. Some ores consume 
days, or weeks, in this process. In the small way, what is 
called a mujfie^ or a common crucible, will answer all pur- 
poses, first breaking the ore into small fragments. A dull 
re 1 heat is a sufficient temperature for most ores. 

Reduction. That is, reducing the ore to its metallic 
state, is generally performed in the small v/ays by means of 
povv^dered charcoal, or black flux, in a crucible, or black 
lead pot. Where the compound is the oxide of a metal, 
the charcoal at a high degree of heat, absorbs the oxygen 
from it, and thus the metal is revived, or reduced to its pure 
metallic form. For this purpose, the ore, as well as the 
charcoal, must be in powder, and mixed together, and the 
heat, in m.ost cases, raised to whiteness. 

Cupellafion. This process is applicable only to gold and 
silver. When either of these metals are in an impure 




3ib CHEMICAL IfiiSkiiALOGW 

State, they are further alloyed with two ot three times their 
weight of lead, hy melting them together. This mass is 
then placed in a kind of dish made of bone ashes, and in 
this state subjected to a sufficient heat to melt it, when the 
lead, together with the impurities, sink dow^n into the cupel, 
and thus leave the gold or silver pure in the dish. 

Muffie. This is a small pot of clay arched over the top 
in the form of an oven, the upper part of which has several 
Fig\ 6S. apertures near the bottom a, to ad- 

mit the air. Fig. OS. In this the 
cupel is placed by the door b, before 
the heat is applied. The muffle is 
then surrounded with coal, and the 
heat raised to whiteness. The use 
of the muffle is to protect the contents of the cupel from 
the contact of the coal, and other impurities. 

Fluxing, This process is necessary w^hen the ore con- 
tains any considerable quantity of silicious, or stony matter. 
The chemical action concerned in the process, consists in 
the union of the silicious matter of the ore, with the flux 
employed. As an example, mix together a given quantity 
of lead or iron ore, wdth four times its w^eight of caustic 
potash, the ore being pulverized, and put the mass into a 
crucible of silver, and having put on the cover, subject it 
to a low red heat for half an hour. Then remove tlie cruel- 
tie and pour in water, which v/ill dissolv e the potash whicli 
has combined with the silex. The w'ater being carefully 
decanted, and the process repeated with hot v\^atcr, the 
silex and other earthy matters will be washed away, and the 
metal left in the crucible. In most instances, it is necessa- 
ry to grind the mass in a mortar, and w^ash ^it through a 
filter before the potash and metal are entirely separated. 
The ore which remains on the filter then becomes in a 
state to be dissolved in an acid, and is to be treated accord- 
ing to circumstances. 

Fusion. This is the conversion of solids into fluids by 
luat. It is usually called melting. Fusion is cflected in 
difl'erent ways, according to the kind of ore to be acted Up- 
on, or its quantity. Minute fragments are melted by the 
blow-pipe, w^hile for larger quantities the crucible, and forge, 
or furnace, are employed. Many substances which are in- 
fusible alone, readily enter into fusion wlien surrounded 
with another substance which acts upon it chemically- or 
which merely serves to retain the heat* 



ANALYSIS OF METALLIC SUBSTANCES. 349 

111 making experiments on ores with the blow-pipe, the 
glass of borax is commonly employed. This is the com- 
mon borate of soda, previously exposed to such a degree of 
heat as to drive off the water of crystallization. What is 
termed the black jinx is also much employed to assist in 
melting refractory bodies. This is made by mixing two 
parts of the cream of tartar with one part of nitre, and de- 
llagrating the mixture in a ladle, or other vessel. 

When the ores of metals are fused in a crucible, the 
pure metal istjpund at the bottom, in the form of a button. 

Elutriation, By this term is meant the repeated washing 
oi any substance, as a precipitate, in order to free it from 
any remains of its solvent. 

In the analysis of ores, these washings must, in certain 
cases, be retained, ^nd added to the filtered solution. When 
this is important, it will be mentioned when the description 
of the analysis is given. 

Eva'poration, This is a process by which the fluid, or 
volatile parts of a solution are separated from those which 
are solid. In some instances heat is employed for this pur- 
pose, while in others the processes suffered to go on by the 
naturul action of the atmosphere. 

When the object is merely to find the weight of the solid 
portion of the mixture, or compound, a gentle heat facili- 
tates the process, but when we wish to obtain fine crystals 
from a saline solution, the action of the atmosphere only Jrs 
much the best. In either case, shallow dishes of porcelain, 
or wedgewood ware, called evaporating dishes, are com- 
monly used, though common white earthern ware dishes 
answer most purposes. 



ANALYSIS OF METALLIC SUBSTANCES. 

The tests, and re-agents required for the analysis of each 
metallic body, will be mentioned in connection with their 
uses, and in describing the several processes by which each 
metal» or its alloy is to be detected. 

Gold, 

This metal is always fow^d in the reguline, or native 
state, but is seldom or never found perfectly pure^ being 

30 



350 ANALYSIS OF METALLIC SUBSTANCES. 

alloyed with various metals, but most commonly with silver 
and copper. 

Tests for Gold. 

Proto-sulphate of Iron gives Metallic Gold. 

Recent muriate of Tin " Purple precipitate. 

Potash and Soda " Yellow do. 

Hydro-sulpliurets *' Black do. 

Tests, or re-agents, are substances generally in the liquid 
form, by which certain other substances are indicated by 
the color, or appearance of the precipitates which the mu- 
tual action of the two bodies produce. Thus a solution of 
iron is instantly turned black by an infusion of nut galls. 
This infusion is therefore a test for the presence of iron in 
solution, and the muriate of tin is a test for gold, by 
throwing down a purple precipitate, and so of the other 
re-agents. 

Assay, 

Assay, or trial, is the means by which the quantity of 
precious or valuable metals is found to exist in a small 
quantity of ore, or alloyed metal. The practical difference 
between the assay and the analysis of an ore, consists in this ; 
The analysis determines the nature and quantity of all the 
substances which the ore, or metallic mixture, contains ; 
whereas the object of the assay is to find how much of the 
particular metal in question is contained in a given quanti- 
ty of the compound under examination. Thus in the as- 
say of gold, or silver, the baser metals they contain, are 
considered of no value, the object of trial on a small quan- 
tity being merely to find the per centage of precious metal 
contained in the whole, of which this is a sample. 

Assay of Gold. 

There are two or three methods by which the quantity 
of gold dispersed through the stony matrix in which it is 
found, is determined. 

The first is, by dissolving the metal in its proper solvent, 
then by a precipitate to throw the metal down, and after- 
wards melt it in a crucible. This is called assaying in the 
moist way. 

The other is, to melt the gold with lead, in a cupel, when 
the lead, combining with the other metals the gold contain- 
ed, sinks into the substance of the cupel, leaving the gold 



ANALYSIS OF METALLIC SUBSTANCES, 



351 



en the surface. This is called assaying in the dry tvay, or 
by cupellation. Gold dust is assayed by this method. The 
last method is by amalgamation with quicksilver, and af- 
terwards driving off this by heat, and thus leaving the gold 
in a nearly pure state. 

The assay in the moist way, the only one it is nesessary 
here to describe, is extremely simple and easily performed. 

Take a certain quantity of the stony matter containing 
the gold, say 400 grains, and having reduced it to a fine 
powder, mix it intimately with four times its weight of dry 
caustic potash, to which a little borax may be added. 
Place this mixture in a crucible, (this should be of silver,) 
and expose it to a dull red heat for an hour. In most cases, 
at the end of this time, the metal will have melted and run 
into the bottom of the crucible. 

Sometimes, however, from the imperfect fusion of the 
mass, or the small quantity of metal it contains, the metal 
is found in globules dispersed in it, and not united in a 
button at the bottom. In this case, the w^hole mass, cruci- 
ble and all, may be placed in an iron vessel and boiled, un- 
til the flux is entirely dissolved, and thrown aw^ay. The 
small globules, together with the other matter which the 
Avater did not dissolve, may now be digested with eight or 
ten times its w^eight of nitro-muriatic acid, in a moderate 
heat, until the w^hole is dissolved, and all action has ceased. 
Then pour off the clear liquor, elutriate any residue that 
may remain with warm w^ter, and add the washings to the 
first solution. 

The gold is now in solution with dilute nitro-m.uriatic 
acid, and must be precipitated by means of a solution of 
proto-sulphate of iron, which is to be added until no more 
precipitate falls. The whole is next to be thrown on a fil- 
ter, elutriated, and the moisture suffered to pass, while that 
which remains is to be mixed with half its weight of nitre, 
and a little borax, and melted in a crucible as before, when 
a button of pure gold w411 be found at the bottom. 

Analysis of native Gold, 

Native gold, or gold as it occurs in its natural state, is 
usually alloyed with various proportions of metallic silver, 
and copper. The proportions of each are found by the fol- 
lowing method. 

Process 1. Digest a given quantity of the metal, sav 100 



352 ANALYSIS OF METALLIC SUBSTANCES, 

grains, with so much nitro-munatic acid as to dissolve the 
whole. During this process, a white flocculent precipitate 
will fall to the bottom of the vessel, which is the silver in 
the form of a chloride of that metal. The clear liquor 
must be decanted, leaving this to be collected, washed, and 
dried on a filter, and then weighed. The proportion of 
pure silver may be estimated at three quarters the weight of 
the chloride. 

Process 2. The remaining solution to which the wash- 
ings of the precipitated silver was added, contains the solu- 
tions of gold and copper. On adding a solution of the 
proto-sulphate of iron, the gold will be precipitated, when 
the clear liquor must be decanted, and the precipitate wash- 
ed and dried, and afterwards reduced to the metallic state 
by fusion with potash and borax, as above directed. 

Process 3. The liquor now remaining contains the cop- 
per, and the littte iron, which was added for the separation 
of the gold. Of the iron no account is to be taken, but the 
copper is to be precipitated by inserting in the liquor clean 
plates of iron, and heating the solution, when the plates 
will be covered with metallic copper, the weight of which 
may be ascertained by first weighing the plates, and then 
finding how much they have gained. If any of the copper 
falls to the bottom of the vessel, this must, after washing 
and drying, be added to that on the plates. 

The weight of each metal thus obtained, will, of course, 
show the proportions in the mass. 



Silver. 

The ores of this metal are considerably numerous, and 
are found in greater or less quantities in nearly every coun- 
try. The most important are the following : 

Native Silver, composed of Silver and a little Antimony. 
Auriferous Silver, — Silver and Gold. 
Sulphuretted Silver, — Silver and Sulphur. 
Red Silver, — Silver, Sulphur, Antimony and Oxygen. 
White Silver, — Sulphus, Antimony and Lead. 
Bismuthic Silver, — Silver, Sulphur, Bismuth and Lead. 
Carbonate of Lilver, — Silver, Carbonic Acid and Anti- 
mony. 
Muriate of Silver,— Silver and Muriatic Acid^, 



ANALYSIS OF METALLIC SUBSTANCES. 353 

Tests for Silver. 

Alkalies give Dark Olive precipitate. 

Plate of Copper " Metallic Silver. 

Muriatic Acid, > ^^ ^ White precipitate, which is 

and salts of, \ " ( soluble in ammonia. 

Tincture of Galls, '^ Brown precipitate. 

The solution of silver gives a permanent black stain to 
the skin and hair, and also to cloth and silk. Indellible 
ink for marking is a solution of nitrate of silver. 

Assay of Silver. 

The proper solvent of silver is nitric acid, and for the 
purpose in question it should be quite pure. This metal is 
not acted upon by the fixed alkalies. 

To ascertain its purity, the ore must be first roasted to 
drive off any sulphur, or arsenic it may contain. It is then 
levigated, and mixed with three or four times its weight of 
cuastic potash, and the whole fused in a crucible, when the 
metal will be found at the bottom. If the metal thus ob- 
tained is foimd to be impure, it must be mixed with lead, 
and subjected to the process of cupellation in the manner 
directed for gold. Or, it may be assayed in the moist v/ay, 
by dissolving it in pure nitric acid, precipitated with com- 
mon salt, the precipitate collected, dried, and mixed with 
carbonate of potash, and fused ; the button of m.etal thus 
obtained, will be pure silver, and its Aveight compared with 
that of the ore, vAU give the per centage. 

Analysis of Silver ores. 

To give the analysis of all the silver ores, would be in- 
compatible with the object of this work. An example or 
two must therefore suiiice. 

Auriferous Silver. 

Process 1. 100 grains of crystallized auriferous silver^ 
which, upon trial, was found to contain only gold, silver, 
and copper, were put into a fiask v/ith two ounces of nitro- 
muriatic acid, and heat applied. Nitrous gas in red fumes 
was disengaged, and a v/hite curd floated in the solution, 
in consequence of the precipitating effects of the muriatic 
acid on the disi^olveJ silver. When cold, the whole was 

30* 



351 ANALYSIS OF I^IETALLIC SUBSTANCES, 

thrown upon a filter, and what remained after washing, was 
dried ; this being chloride of silver, was afterwards redu- 
ced to the inetallic state, with a little black flux, in a cru- 
cible. 

Process 2. The washings of the silver being added to the 
filtered liquor, a solution of proto-sulphate of iron was 
poured in, until no further precipitation followed. By this 
the gold was thrown down in the metallic form, which was 
afterwards, washed, dried, and reduced to a button, by means 
of nitre, and weighed. 

Process 3. Having thus obtained the gold and silver, 
the Vv'ashings of the last process were added to the solution 
wliicli now contained the copper only. This was precipita- 
ted by a clean plate of iron, and afterwards dried and 
weighed. The number of grains each metal weighed, 
showed their propoitions in the ore, and the sum of the 
whole indicated the loss of less than a grain. 

Aiitimojiial Silver, 

Process 1. Of u^ntimonial Silver^ 100 grains were pul- 
verized and digested, with ten times its weight of nitric 
acid. A portion being undissolved, was washed and dried, 
and found to be silex. 

Process 2. The washings of the silex being added to 
tlie iiltered solution, occasioned a turbidness, and on pour- 
ing in more v»'ater, a precipitate fell down, which was oxide 
of bismuth, contained in the ore. 

Process 3. i\Iuriate of Soda being now added the 
whole of tlie silver was precipitated, v.hich, being washed 
and dried, arnounted to three fourths of the metal exam- 
ined. 

Muriate of Silver. 

This is tlie richest of the silver ores, sometimes yielding 
■^5 per cent, of the metaL It is known to the miners by 
the name of hoj'n silver. Its composition is silver and mu- 
riatic acid, with generally some foreign impurities. 

Process 1. Mix the powdered ore with four lim.es its 
weight of carbonate of potash, or soda, and flux in a cru- 
ci])ie. When tl^e fusion is complete, dissolve the mass with 
boiling water, elutriate what remains undissolved, and then 
digest it in nitric acid. This portion must be kept sepa- 



A.NAL¥SiS OF METALLIC SUBSTANCES. 355 

rate, and the silver it contains precipitated with muriate of 
soda, and reduced with black Aux in a crucible. 

Process 2, The alkaline liquor, or the washings of the 
fused mass containing the muriatic acid of the ore, combin- 
ed with the soda, is to be brought to the point of saturation, 
with distilled vinegar. This will throw down the alumine, 
which this ore usually contains, in the form of a w^hite 
powder, which must be washed, dried, and weighed. 

Process 3, The remaining solution now contains the 
muriatic acid of the ore, and probably some portion of the 
soda, in which it was fluxed. This is to be evaporated to 
dryness, and the mass then digested for several days in al- 
cohol. This will take up the uncombined soda, while the 
other portion of soda will have combined with the muriatic 
acid of the ore, forming tnuriate of soda. The liquor is 
then to be evaporated, and the muriate of soda weighed, 58 
parts of which, are equal to 24 of muriatic acid. 

Process 4. If the ore contains sulphuric acid, which is 
often the case, the salt remainixig after the third process, is 
to be dissolved in v/ater, and tested with acetate of barytes, 
by which it will be precipitated. This acid is generally in 
very small quantities, and will hardly vary the result. 

Meixuri/. 

This metal is sometimes found in the native state, but the 
source whence the greater portion is obtained, is from the 
sulphuret of mercury, or native cinnabar. 

The ores of this metal are. 

Cinnabar, composed of Mercury and Sulphur. 

Native Amalgam, — Mercury and Silver. 

Horn Mercury.— -Mercury Oxygen, Muriatic and Sul« 
phuric Acids. 

Tests for Mercury. 

The presence of this metal in solution, may be detected 
as follows ; the re-agents being on the left, and their ef- 
fects on the right. 

A plate of copper, Metallic Mercury. 

A plate of iron. Dark powder. 

Fresh lime water, Orange precipitate. 

Ferro-prussiate of potash. White do. 

ilydro-sulphurets, Black do. 

(sallic acid, OranofC vellow. 



356 ANALYSIS OF METALLIC SUBSTANCES, 

In ihe large way, mercury is obtained by mixing the sul- 
phuret, or native cinnabar, with iron filings, or lime, and 
distilling the mixture in iron retorts. The sulphur of the 
mercury combines with the iron, or lime, and leaves the 
metal free, which being volatilized by the heat, is condensed 
in a cold vessel in the metalic form. 

An example of this process may be made in a glass tube, 
hj means of a blow-pipe, by placing at the bottom, or sealed 
end of the tube, a piece of cinnabar, and inserting also a 
bright slip of copper. On applying the heat of the blow-pipe 
carefully to the ore, through the tube, the metal will sub- 
lime and attach itself to the copper. 

Analysis of the ores of Mercury, 

The analysis of these ores is simple, as they seldom con- 
tain many foreign ingredients. 

Native Cinnabar. 

This ore, as we have already seen, is composed of mer- 
cury and sulphur. Its analysis may be thus effected. 

Process 1. — Take 100 grains of the ore reduced to pow- 
der, and digest it with 8 or 10 times its weight of muriatic 
acid, adding now and then a few drops of nitric acid, to 
make the solution more perfect. When all action ceases, 
pour olT the clear liquor, w^ash the residue, and dry it with 
a gentle heat. This Avill contain the sulphur, and such 
other matter as was insoluble in the acid. 

Process 2. — The insoluble matter after drying, is to be 
heated in a platina crucible, or in the absence of this, in the 
bowl of a tobacco-pipe, until all the sulphur is burned away, 
when, on re-weighing, the loss of weight will indicate the 
quantity of sulphur in the 100 grains. 

Process 3. — The clear liquor poured off in process 1, is 
now to be tested by placing^ little in a test tube, and adding 
tinct. of nut-galls, when, if it contains iron, a dark precipi- 
tate will fall. Then insert a slip of clean iron, and if it 
contains copper, a coat of the metal will cover the slip. 
If the solution is found to contain only copper and iron, in 
addition to the mercury, the whole must be evaporated to 
dryness, taking care not to employ so much heat as to 
decompose the muriate of mercury. 

Process 4. — The dry mass obtained by the last process 
must be dissolved in pure water, which will dissolve tlie 



ANAl.Y.SIli or METALIC SUBSTANCES, o57 

saUis of mercury and copper, but will leave the iron behind 
in tlie state oi' a pcr-oxide. 

Process 5. — Immerse into the watery solution a clear plate 
of iron, and i^ently heat it, when both the copper and mer- 
cury will fall down. This being thrown on a filter, and 
well washed, must be dried and weighed, and then exposed 
to a red heat, which will drive off the salt of mercury, leav- 
ing the copper behind. Then on weighing the copper, the 
amount of the salt of mercury will be indicated, and the 
weight of the metal may be readily known, as the salt, which 
. is the proto-chloride of mercurv, contains 84 parts mercury, 
and 1(3 chlorine. 

Ars€7iic. 

The form under which this metal is best known, is that 
of the white oxide, w^hich is the arsenlous acid. The metal 
from this is readily obtained by mixing it with a little black 
tlux, or powdered chalcoal, placing the mixture at the bot- 
tom of a thin glass tube, and applying the heat of a candle, 
or lamp. The charcoal will absorb the oxygen, and the 
metal will rise, and be condensed on the inside of the tube, 
coating it vvith a brilliant white metal. 

No mines are worked for the purpose of obtaining arsenic, 
a sufficient supply of its oxides being obtained in the pro- 
cess of working the cobalt mines of Saxony and GermanVi^ 

The ores of arsenic present the following varieties. 

Native arsenic, Arsenic with iron. 

Pharmacolite, Arsenic, lime and oxygen. 

Arsenical pyrites, Arsenic, iron and sulphur. 

Orpiment. > * . i i i 

Realger, \ Arsenic and sulphur. 

^Vhite arsenic, Arsenic and oxygem 

The presence of arsenic in any substance is readily known 
by the strong smell of garhe wdiich it emits wdien exposed 
to heat. 

It will hardly be necessary to go through the processes 
of assaying, or analysing the ores of arsenic, since the metal 
in the pure state is of no value, as it turns to an oxide by 
mere exposure to the atmosphere. 

The best methods of ascertaining the presence of this 
metal, are by the garlic odor above noticed, and the reduc- 
tion of It in a glass tube, bv means of the black flux above 



358 ANALYSIS OF METALLIC SUBSTANCES. 

described. It is said, however, that wliere the metal is in 
the state of an oxide, or acid, no garlic odor is emitted, the 
presence of metalUc arsenic being necessary for the pres- 
ence of this test. But if the oxide be heated in contact 
with charcoal, or any other reducing agent, the metal will 
always be present, as above explained. 

Still the most sure test is the reduction of the metal, since 
the garlic odor may possibly be so nearly imitated by some 
other substances, as to occasion mistakes, a matter which 
may in some instances, as in suspicion of poisoning, jeopard- 
ize human life. 

In such cases, if the chemist is called on to examine the 
contents of the stomach, or a portion of the vehicle in which 
it is supposed the arsenic was given, the fluid may be evapo- 
rated to dryness, and then mixed with black flux, and dis- 
tilled in a common retort, with the heat of a lamp. The 
arsenic, if any be in the mixture, will rise and coat the in 
side of the neck of the retort, giving it a metallic lustre 
nearly resembling quicksilver. A little of this detached, 
and heated on charcoal, if it emits the garlic odor, will de- 
cide the question beyond any doubt, that it is arsenic. 

Cobalt 

Most of the cobalt used in the arts comes from the Saxon 
mines, under the name of zaffree. This consists chiefly 
of solicious matter containing a small portion of the oxide 
of the metal. 

The ores of cobalt, which are found in many countries, 
are chiefly the following. 

^ , 1, .^ { Cobalt, arsenic, sulphur, and some- 

Cobalt pyrites, s ^- • j 

^ -^ ( times iron and copper. 

Red cobalt. Cobalt and arsenic acid. 

Earthy cobalt. Oxide of cobalt, iron and arsenic. 

Sulphate of cobalt, Oxide of cobalt, and sulphuric acid. 

Tests of Cobalt 

The solutions of the salts of this metal are either red, 
green, or blue, depending on the quantity of cobalt they 
contain. 

Potash and soda. Blue precipitate. 

Ferro-prussiate of potash. Green precipitate. 
Carbonates, , Red precipitatCa 



ANALYSIS or METALLIC bUBSTANCfiS, 369 

All the ores of cobalt when melted with borax, give a deep 
blue bead. This is the readiest and most certain method 
of ascertaining the presence of that metal. 

Analysis of Cobalt, 

The cobalt pyrites, or arsenical cobalt, not only contains 
the two substances from which its scientific name is derived, 
but is often mixed with copper, iron, nickel, and bismuth 
also. Hence the analysis of this variety is considerably 
complicated. 

Process 1. — Mix one part of finely powdered arsenical 
cobalt, w ith three parts of nitre, in a crucible, and submit it 
to a red heat for one hour. A chemical interchange of ele- 
ments will ensue, and the arseniate of potash will be the re- 
sult. Dissolve this in nitric acid, and if any residue remains 
undissolved, mix it with nitre, and heat in a crucible as 
before ; then digest in nitric acid and filter. 

Process 2. — Evaporate the nitric acid solution with heat, 
in order to drive off any excess of acid, and then dilute with 
a large quantity of water. This will separate the bismuth, 
which will fall down in form of a white powder, which is to 
be separated by decantation, dried and weighed. 

Process 3. — Immerse in the solution from which the bis- 
muth has been separated, a slip of clean iron of known 
weight. This will precipitate the copper in the metallic 
form on the iron, which must be weighed again to find the 
weight of copper. Then evaporate the remaining liquor to 
dryness, with heat. 

Process 4. — Digest the dry mass of process 3, in a solu- 
tion of caustic ammonia. This will dissolve the cobalt and 
nickel, but not the iron. 

Process 5. — Drive ofT the excess of ammonia by heat, 
taking care not to continue the evaporation so as to produce 
any precipitate, then add caustic potash to the solution, and 
throw the whole on a filter, by which the nickel will be 
separated, while the clear liquor passes the filter. 

Process 6. — Boil the clear liquor, which has passed the 
filter, and oxide of cobalt will fall, and continue the evapo- 
ration to dryness. 

Process 7. — Mix the oxide obtained by the last process 
with charcoal powder in a covered crucible, and submit it to 
a strong heat for half an hour, or until reduction is effected. 
A button of cobalt will be found at the bottom of the cru- 
cible. At first, the metal is bluish grey, but turns reddish 



« 



360 ANALYSIS OF .1I£TALLK iJl BSTANCE^. 

grey by exposure to the air. It is brittle, diflicuh of fusion^ 
and has a specific gravity of about 8. 

The result of each process being weighed, will show, not 
only the comparative quanty of each, but the sum of 
the w^hole will determine the per centage of the cobalt in 
the ore. 

Bismuth* 

The ores of bismuth are rare, and in gener^fl it is found 
only in small quantities at a place. Most of the bismuth 
Used in the arts, is obtained in the processes for making 
smalt from the ores of cobalt. 

The ores of cobalt being roasted and broken into small 
pieces, are mixed with certain quantities of potash and 
ground flints. This mixture is put into large clay crucibles, 
and fused with a strong heat for 12 hours, at the end of 
which, the blue glass, or smalt, will be perfectly formed. 
At the bottom of the crucibles, the bismuth and nickel, 
(more or less of which are contained in the cobalt ores.) are 
found reduced to their metallic states. These are readily 
separated, in consequence of the low degree of heat re- 
quired to melt the bismuth. 

Bismuth is found under the following forms, viz : 

Native bismuth, The pure metal. 

Sulphuret of bismuth, Bismuth and sulj)hur. 

Oxide of bismuth, Bismuth and oxygen. 

The ores of the metal are very easih^ reduced, the process 
requiring only a blowpipe, and a piece of charcoal. The 
ore being fused, the charcoal absorbs the oxygen, and the 
metal instantly appears. 

Tests for Bisiniith. 

The solutions of this metal are white, and Avatcr alone, 
throws down a ^ne white oxide. 

Gallic acid. Greenish yellow* 

Ferro-cyanate of potash. Light yellow. 
Alkalies, White precipitate. 

Assay. 

The assay of the ores of bismuth is easily eflected. A 
given portion of the ore is to be digested in the f:?;;a c f pow- 



ANALYSIS OF METALLIC SUBSTANCES. 361 

der, in nitric acid, and the solution filtered, and washed with 
watei^, containing a little of the same acid, by pouring this 
on the filter. The solutions being mixed, pour in 8 or 10 
times their quantity of pure water, when a copious white 
precipitate will fall, which is easily reduced to the metallic 
state with a little black flux, or charcoal in a crucible. The 
heat for this purpose must be gentle, and the crucible cov- 
ered, otherwise the metal after its reduction, will be lost by 
sublimation. 

If the bismuth is mixed with other metals, which dissolve 
in nitric acid, they still remain in the solution, not being 
precipitated by the mere addition of water, as in the case 
of bismuth. 

Analysis. 

Supposing the ore to be composed of bismuth, lead, iron, 
sulphur, and silex. 

Process 1. Pulverize the ore, and digest in nitric acid 
with heat until nothing more is dissolved ; silex and sulphur 
will remain, while the metals will be dissolved. Throw the 
whole on a filter, and wash by pouring on dilute acid, — the 
sulphur and silex will remain, and must be collected, dried, 
and weighed. 

Process 2. The clean liquor which passed through the 
filter, being diluted largely with water, the oxide of bismuth 
will fall, and after descanting the liquor, is to be dried, and 
reduced with black flux as above directed. 

Process 3. The solution is now supposed to contain 
only lead and iron, both in the form of nitrates. On the 
addition of sulphate of soda, the lead will be thrown down 
in the form of an insoluble heavy, white precipitate. This 
is to be collected by passing through the filter, dried and 
weighed. 

Process 4. To the remaining solution, add caustic am- 
monia in excess, by which the oxide of iron will be thrown 
down, (vr'iile the liquor will assume a fine blue color,) and 
must bo separated by the filter, and washed by more ammo- 
nia. Tiie oxide being dried, may be reduced to the mag- 
netic state by heating in a covered crucible vrith some 
unctuous substance, as linseed oil. 

Process 5. The ammoniacal solution of the last process 
must be a little more than saturated with some acid, and on 
immersing a slip of iron or zinc, the copper which it con- 

31 



362 ANALYSIS OF METALLIC SUBSTANCES. 

tains will be obtained in the metallic form. For this pur- 
pose the slip must be previously weighed, as already directed, 

Reductio7i. 

The methods of reducing the ores of bismuth, are very 
simple, it being only necessary that they should be broken 
into fragments, and thrown upon burning charcoal or wood. 
In some instances the workmen seek out a hollow tree, or 
stump, and having filled it with alternate layers of brush 
wood and ore, set the whole on fire, and when the fuel is 
consumed, and the place cold, they find the bismuth among 
the ashes. 

Uses, The only use of bismuth in its metallic form is 
that of forming a very fusible solder, when alloyed with 
other metals. 

The oxide of bismuth is prepared by precipitating it from 
a solution in nitric acid by means of water as already di- 
rected. When a little muriatic acid is added to the nitric 
solution, the precipitate is composed of small glittering 
scales, and in this state is sold by perfumers under the 
name of pearl powder, and is used as a cosmetic ; but it is 
well known that the application of such substances soon 
render their use absolutely necessary, as the skin soon be- 
comes permanently darkened thereby. 

Antimony. 
This metal occurs under the following forms : 

Native antimony, Antimony, arsenic, silver, iron. 

Sulphuret of antimony, Antimony and sulphur. 

T> , ,. ^ Antimony, sulphur, and oxy- 

Ked antimony, { 

•^' I gen. 

T^T. 1 !•/» ,. \ Antimony, arsenic, nickel, sul- 

Nickeliferous antmiony, ) v, 

White antimony, Antimony, oxygen, and silex. 

Before the blow-pipe, the ores of antimony are easily 
reduced, generally with the emission of a sulphureous, and 
arsenical odor. By continuing the heat, the reduced metal 
is entirely dissipated in the form of a white oxide. 

Tests for Antimony, 
The solutions of antimony in muriatic acid are thrown 



ANALYSIS OF METALLIC SUBSTANCES. 363 

down by mere dilution with water. The precipitate is a 
white 5ubmuriate. 

A plate of iron, Black powder of the metal. 

Sulphuretted hydrogen, Orange precipitate- 

Assay, 

The method of assaying the ores of this metal, will be 
understood by the following analysis : 

Process 1. A portion of the ore reduced, as usual, to fine 
powder, was digested with heat in a mixtute of 4 parts of 
muriatic, and 1 of nitric acid, until every thmg soluble was 
dissolved. The liquor being filtered, there remained a resi- 
due of sulphur and silica. This being dried, was placed in 
a spoon, and held over the flame of a spirit lamp, until the 
blue flame ceased, and consequently the sulphur had burned 
out. The loss of weight thus gave the proportion of sul- 
phur and silex. 

Process 2. The filtered solution being now diluted with 
pure w^ater, the submuriate of antimony fell down, w^hich 
being dried, w^as reduced to the metallic state, with a little 
black flux, in a crucible. In doing this, the heat must not 
be strong, lest the metal should be sublimed. 

Process 3. The remaining liquor, reduced by evaporation, 
was diluted wdth water, when another portion of the anti- 
mony was obtained, and added to the former quantity. 

Process 4. The solution being now tested in small por- 
tions, in a test tube, w^as found to contain iron and lead. 
The iron was precipitated with caustic ammonia, and the 
lead afterwards, by sulphate of soda, hoth of w^hich were 
reduced by means of charcoal powder in a crucible. 

Some of the ores of antimony contain silver, which may 
be known by the fall of an insoluble muriate of the metal, 
during the first process, and therefore mixed with the sul- 
phur and silica. In order to separate it, the first residue 
must be digested in liquid ammonia, which will dissolve the 
muriate of silver. On saturating this with muriatic acid, 
and immersing a slip of copper, the silver will be obtained 
in the metallic state. It is hardly necessary to repeat, that 
in all such cases, the slip of copper must be weighed, both 
before and after immersion. 

Reduction of Antimony. 
The reduction of this metal is very simple and easy. The 



364 ANALYSIS OF METALLIC SUBSTANCES. 

ore, being broken into small pieces, is placed on the floor 
of a furnace so constructed that the flame shall pass over it. 
This is called a reverberatory furnace. The heat is at first 
gentle, or drive ofl' the sulphur, and afterwards increased, 
with the addition of charcoal, by which the metal is reduced 
to the metallic state. 

The antimony this obtained is impure, being almost al- 
ways mixed with portions of some other metal, as lead, cop- 
per, or arsenic, and therefore for chemical or medicinal 
purposes, must be dissolved in nitromuriatic acid, precipi- 
tated with water, as above directed, and then reduced by 
charcoal, or flux. 

Lead, 

The ores of lead are very numerous, the metal being min- 
eralized by several of the metallic and mineral acids, as 
well as by phosphorus, sulphur, and oxygen. They difler 
very materially in appearance and weight, in consequence 
of the different agents by which they are mineralized, and 
the substances with which they are combined. Some of 
them, as the sulphuret, are rich in the metal, while others 
are not worth working. 

Varieties, 

Sulphuret of lead, Lead and sulphur. 

Oxide of lead. Lead and oxygen. 

Carbonate of lead, Lead and carbonic acid. 

Muriate of lead. Lead and muriatic acid. 

Phosphate of lead, Lead and phosphoric acid. 

Arseniate of lead. Lead and arsenic acid. 

Sulphate of lead. Lead and sulphuric acid. 

Molybdate of lead. Lead and molybdic acid. 

Chromate of lead. Lead and chromic acid. 

"With respect to the composition of these varieties, we 
have only named the principal ingredients, and from which 
they have derived their names ; but in addition to these, 
nearly every lead ore except the sulphuret, contains foreign 
admixtures, as copper and iron, and in most cases, the ores 
named are mixed with each other, so that the muriate, or 
carbonate, will perhaps contain both these ores, with the 
addition of chromate, sulphate, <fec. Most of these ores, 
however, may be reduced to the metallic state with the 
blowpipe, on charcoal. 



ANALYSIS OF METALLIC SUBSTANCES* 365 

Tests for Lead^ 

Sulphate of soda, White precipitate, 

Ferro-cyanate of potash, Do. do. 

Infusion of galls, Do. do. 

Sulphuretted hydrogen, Black precipitate. 

Assay. 

Notwithstanding the complicated admixture of these ores, 
their assay is sufficiently simple. Reduce a given weight 
of the ore to powder, and place it on a muffle, and apply a 
degree of heat just sufficient to volatilize the arsenic and 
sulphur, or until, on moving the muffle from the fire, the 
smell of these substances are no longer emitted. Having 
thus finished the roasting, the ore is to be levigated^ — mixed 
with two or three times its weight of black flux, and a little 
muriate of soda, and exposed in a crucible to a strong heat. 
When the crucible is cold, a button of lead will be found 
at the bottom, which on being weighed and compared with 
the weight of the ore, will shew the percentage. 

If the ore to be assayed is galena, its own weight of black 
flux will be sufficient to effect is reduction, it first being 
roasted as above directed, and pulverized. 

In the roasting of lead ores, care must be taken not to 
fuse them, as it is much more difficult to dissipate their vol- 
atile parts, after fusion, than before. 

Analysis, 

Supposing the ore to be the carbonate of lead, mixed with 
green oxide of copper, and oxide of lead, its analysis may 
be performed as follows : 

Process 1. Having roasted the ore, put 100 grains into a 
flask, the weight of which had been previously ascertained, 
and pour on it by degrees a quantity of nitric acid, diluted 
by its own weight of water, the weight of the acid being 100 
grains. Eff'ervescence will instantly begin, \vhich having 
subsided, the comparative weight of the bottle and its con- 
tents will shew the weight of the carbonic acid \vhich 
escaped. 

Process 2. The clear liquor being decanted into a tall 
glass jar, drop in a solution of sulphate of soda, until a w^hite 
powder ceases to fall. The sulphate of lead thus separated 
must be washed, dried, and reduced with black flux, or the 

31* 



366 ANALYSIS OF METALLIC StTfiSTANCES'. 

quantity of lead may be readily estimated by the proportions^ 
of the metal and acid in the salt. 

Process 3. The copper now remaining in the solution, 
may be obtained by immersing in it a plate of iron, or zinc, 
and suffering it to remain at rest for 24 hours ; the copper 
will thus fall in the metallic state. If on testing the solu- 
tion with ammonia, a blue tint is given it, copper still re- 
mains, and a gentle heat must be applied, the metallic plate 
remaining in its place, when the whole of the copper will 
fall, and being collected may be melted into a button, or by 
finding the addition to the weight of the plate of iron, or 
zinc, its weight is known. 

Reduction* 

The great quantities in which the ores of lead are found, 
together with its cheapness, and the facility with which it 
is reduced, render it unnecessary to observe that care and 
nicety in its reduction that are observed with respect to the 
more scarce and valuable metals. 

Galena is the only ore, which is worked for the express 
purpose of obtaining this metal. This is selected as free as 
possible from stony matter, and after being broken, is roast- 
ed in large furnaces, built for the purpose. By this process 
the sulphur and arsenic, if it contains the latter, is driven 
off, and the ore is brought to a proper state for the smelting 
furnace, where it is thrown in, mixed with charcoal. The 
heat of the furnace is urged by bellows, and is kept red un- 
til the ore melts, and running through the charcoal, is re- 
duced to the metallic state. It is let out at the bottom of 
the furnace, and cast into pigs for market. 

Most of the lead of commerce contains a small quantity 
of silver, and in some instances the ores of this metal con- 
tain a quantity sufficient to pay the expence of extracting it. 
When the silver amounts to 12 or 14 ounces to the ton of 
lead, the former is separated by exposing the lead to a high 
degree of heat, in a furnace so constructed that the air 
shall constantly pass over the heated metal, and by which 
it is oxidated, or converted into litharge, while the silver 
remaining unchanged, is collected and refined. 

The litharge is afterwards reduced to the metallic state, 
by the simple process of melting it with charcoal in a close 
furnace, by which the oxvgen is absorbed by the burning 
fuel. 



ANALYSIS or METALLIC SUCStANC£S. 36t 

Copper, 

Copper is often found in the native state, but more gene- 
rally in small quantities. That which is used in commerce 
and the arts, is chiefly extracted from its ores, which are 
very numerous, it being found combined with oxygen, sul- 
phur, arsenic, carbonic acid, sulphuric acid, muriatic acid, 
&c. The following are among the most important species 
of this ore, 

Sulphuret of copper, Copper, sulpher and iron. 

Grey copper. Copper, sulphur, iron and arsenic. 

Red oxide of copper. Copper and oxygen, and iron, 

Carbonate of copper. Copper and carbonic acid. 

Muriate of copper, Copper, muriatic acid, and water* 

Phosphate of copper. Copper and phosphoric acid. 

Sulphate of copper. Copper and sulphuric acid. 

Arseniate of copper. Copper and arsenic acid. 

Like the ores of lead, those of copper are variously inter- 
mixed, and often contain several more ingredients than are 
mentioned as belonging to their composition. For the de- 
scription of these ores, the author must refer to his treatise 
on Mineralogy, where an account of each will be found. 

Tests for Copper* 

It is understood of course, that the metal is dissolved 
in some acid, to saturation, before the application of the 
test. 

Plate of iron, Metallic copper. 

Potash, Green precipitate. 

Ammonia, Azure blue color, 

Ferro-cyanate of potash. Reddish brown precipitate* 
Infusion of galls. Brown precipitate. 

Sulphuretted hydrogen, Brownish black precipitate. 

Action of the Blowpipe on Copper ores. 

The oxides of copper may be reduced on charcoal by the 
blowpipe. The carbonates are infusible without addition, 
but with borax form a green glass, and yield a metallic glo- 
bule. The varieties containing sulphur and arsenic, yield 
white fumes, and give the odor of these substances respec- 
tively. 



368 ANALYSIS OF METALLIC SUBSTANCES* 

Assay of Copper ores. 

As nearly all the ores of copper contain sulphur or arse- 
nic, or both, they must in the first place be roasted with a 
gentle heat, in order to expel these substances. After this 
is done, the ore is to be pulverized, and mixed with twice 
its weight of black flux in a crucible, and exposed to a 
strong heat, as that of a smith's forge, for about half an 
hour. Should the globules of revived metal not readily 
form a button at the bottom, a little common salt thrown in, 
will render the fusion more complete. The little mass of 
pure copper will show the percentage of metal in the ore. 

Analysis of Copper ores. 

Process 1. Having roasted a specimen of the sulphuret 
of copper, previously weighed, on weighing it again, the 
amount of sulphur will be known. Then pulverize and di- 
gest in nitric acid, which will dissolve the copper, and iron 
it may contain. Filtrate the solution, which will separate 
the silex and any sulphur which the roasting did not expel. 
These being dried and weighed, the sulphur may be burn- 
ed away in a spoon. The weight of silex will thus be 
known. 

Process 2. Precipitate the copper from the solution 
with a slip of clean iron, suffering the whole to remain at 
rest for 24 hours. The iron being weighed before, and 
after immersion, will show the weight of copper. 

Process 3. Add caustic ammonia to the remaining solu* 
tion, which will throw down the iron in the state of an ox- 
ide. Then filter, and collect the iron, estimating the weight 
of the metal by that of the oxide, as shown by the table of 
equivalents. 

Process 4. If the liquid is colored blue by the ammonia 
it still retains copper, and must be acidified with nitric 
acid, and the bar of iron again immersed, and the action 
assisted by a gentle heat, when all the copper will fall on 
the iron, and its weight must be added to the former. 

Considerable experience is necessary, in order to make 
a satisfactory analysis of a copper ore, especially when it 
contains but a small quantity of the metal, mixed as these 
ores often are, with a variety of foreign ingredients. In 
making the assay also, a good deal of patience is often re- 
quired, and the process several times repeated, before the 



ANALYSIS OF METALLIC SUBSTANCES. 369 

result can be depended upon, unless the operator has had 
much experience in the art of analysis. 

In Germany, where the art of smelting and refining the 
metals are carried to a high degree of perfection, every par- 
cel of copper ore is assayed by three several persons before 
its reduction. 

Reduction of Copper Ores* 

The sulphuret of copper is one of the most abundant 
ores, and it is from this species that most of the copper of 
commerce is obtained. The processes are lengthy, requir- 
ing several months before the metal is ready for market. 

The ore, which is often contained in slate stone, is first 
broken into small pieces, and roasted in kilns with wood. 
A small quantity of fuel is, however, only required for this 
purpose, for the quantity of sulphur is such, that after it is 
once set on fire, the mass continues to burn, when the quan- 
tity of ore is great, for four, or five months, without further 
addition of fuel. 

When the ore ceases to burn, this part of the process is 
finished, and the sulphur which has sublimed by the heat, 
and is retained in long chimneys, is removed. The ore is 
then transferred to a reverberatory furnace, and mixed with 
charcoal, where it is submitted to a white heat for several 
hours, when the copper in the metallic state, but mixed with 
many impurities, is obtained. It is afterwards refined, by 
being repeatedly melted with charcoal, and granulated by 
pouring it into water, when it becomes malleable copper. 

In those ores of copper Avhich contain arsenic, the slow 
roasting above described is omitted, the ore being at once 
thrown into the furnace, and the sulphur and arsenic dissi- 
pated in a few hours. In some establishments the refining 
is done by mixing the impure copper with a portion, say 6 
per cent of lead, and stirring the melted metals together, 
by which means, the lead unites with the impurities, and 
both are skimmed oflf together. The workmen consider 
the process finished, when on dipping in an iron rod, and 
then plunging it into water, the copper with which it is 
coated, readily separates from the iron. 

Tin, 

The ores of tin have been found in but a few localities. 
They are always found in primitive rocks, generally in 



370 ANALYSIS OF METALLIC SUBSTANCES. 

granite, and are associated with copper, and iron. Its chief 
varieties are — 

Oxide of tin, Tin, oxygen, iron, and silex, 

Wood tin, Oxides of tin, and iron, 

Sulphuret of tin. Tin, sulphur, copper and iron. 

The oxide of tin occurs disseminated, massive, and in 
crystals, often of regular, and beautiful forms. Wood tin 
is of a light brown color, and when broken, sometimes re- 
sembles in texture, the grain of wood, or root of a tree, 
hence the name wood tin. It is a purer oxide than the 
above variety, which is called tin stone, Sulphuret of tin 
is the most impure variety, being mixed with copper, iron, 
and often other impurities. 

Action of the blowpipe on the ores of Tin, 

The oxides of tin, before the blowpipe, decripitate strong- 
ly, but when in powder and mixed with charcoal, are reduc- 
ed to the metallic state, though with considerable difficulty. 
The sulphuret, treated in the same manner, melts into a 
dark scoria, but is not reduced. 

Tests for Tin. 

The salts of tin are uncolored, or white, The tests for 
solutions holding the metal in the state of protoxide, are as 
follows : 

Muriate of gold. Purple precipitate. 

Muriate of platina. Orange do. 

Ferro-cyanate of potash. White do. 

Per-chloride of mercury. Black do. 

Plate of lead. Metallic tin. 

Metallic tin has a silvery lustre, not readily tarnished by 
exposure. It always may be known from other metals by 
the peculiar crackling noise it makes on being bent. 

Assay of Tin, 

In the dry way, the assay of tin ores is sufficiently simple. 
Having reduced 100 grains of the ore to powder, place it in 
a crucible, and expose it to a low red heat, by which the 
sulphur and arsenic, if it contain any, will be dissipated. 
The ore is then to be mixed with charcoal, moistened with 
a little linseed oil, and exposed to a bright red heat, in a 



ANALYSIS OF METALLIC SUBSTANCES. 371 

covered crucible. A button of the metal will be found at 
the bottem, which, on being weighed, will show the per- 
centage the ore contained. 

Analysis of the ore. 

Process 1. Mix the ore, being reduced to powder, with 
five or six times its weight of caustic potash, and submit the 
mixture to a red heat for half an hour in a silver crucible. 
Digest the grey mass thus formed, in hot water, and if any- 
insoluble matter still remains, it must be mixed with more 
alkali, and again heated as before. 

Process 2. Filter the alkaline solutions, and if any thing 
remains, dissolve it in muriatic acid, and add this to the alka- 
line solution, which must be super-saturated with muriatic 
acid, and then evaporated to dryness. The dry mass must 
now be digested in hot water, which will take up all except 
the silex, which will remain after filtration. 

Process 3. The tin and copper, if the ore contained any, 
will now be contained in the muriatic solution, which is to 
be saturated with carbonate of potash, when a precipitate 
will fall. If this is white, it is to be collected, and the pro- 
cess ended by reducing it with charcoal powder, and a little 
oil or resin. But if it has a greenish appearance, it contains 
copper, and the precipitate must be re-dissolved in muriatic 
acid, when on the immersion of a slip of tin of known 
weight, the copper will cover it in the metallic state, and 
the difference of weight will show that of the copper. 

Process 4. The solution being now deprived of the cop- 
per, a plate of zinc immersed in it will throw down the tin 
in its metallic state, which, when dried and fused, will in- 
dicate the per centage contained in the ore. 

Reduction of Tin Ores. 

The reduction of what is called mine tin, that is, ore 
which is extracted from the mines at Cornwall in England, 
is reduced in the following manner. The ore is first stamped 
or pounded, and at the same time washed by a running 
stream, which carries away much of the earthy matter. It 
is then sent to the furnace to be roasted, after which it is 
again washed in order to purify it as much as possible. The 
ore thus prepared, is mixed with coal and a portion of slacked 



372 ANALYSIS OF METALLIC SUBSTANCES. 

lime, and smelted in a reverberatory furnace, which is about 
seven feet long, five broad, and fifteen inches deep. The 
usual charge of ore is 7 cwt. which yields about two thirds 
of its weight of tin. 

To obtain 100 pounds of tin, there is consumed in the 
roasting, 38 pounds of coal, and in the smelting, 170 
pounds of coal, in all 208 pounds, or a little more than twice 
the weight of the tin obtained. 

Refined Block Tin, 

The tin obtained by the above process, is afterwards re- 
fined by melting it with a gentle heat, in a reverberatory fur- 
nace, and allowing it to run off as fast as it becomes liquid, 
into an iron kettle, with a small fire under it. Thus the 
least fusible substance with which the metal is alloyed, 
are left behind. The tin in the kettle is kept fluid, and is 
further purified by taking it up in small quantities at a time, 
and pouring back again, by which the more oxydable parts 
are made to swim on the surface, and are skimmed off. 

Zinc. 

The ores of this metal are not numerous, nor are they 
very universally difiiised, though in small quantities, they 
often occur among the ores of lead. The principal varie- 
ties of zinc are the followinof : 

Sulphuret of zinc. Zinc, sulphur, and iron. 

Red oxide of zinc. Zinc, oxygen, iron and manganese. 

Electric calamine. Zinc, oxygen, and silex. 

Sulphate of zinc. Zinc, sulphuric acid, and water. 

Carbonate of zinc, Zinc, and carbonic acid. 

Action of the blowpipe on Zinc ores. 

Before the blowpipe, on charcoal, the ores of zinc first 
evolve their volatile parts, as sulphur, and by continuing the 
heat, some of them become white, or form scoria, while oth- 
ers emit white fumes, which is an oxide of the metal. With 
glass of borax, they form a kind of translucent enamel, or 
if copper is present, the enamel is green. In the dry way, 
therefore, the tests of this metal are not satisfactorv. 



ANALYSIS OF METALLIC SUBSTANCES. 373 

Tests for Zinc. 

This metal is readily dissolved in all the mineral, and in 
several of the vegetable acids. The tests for its presence 
in solutions, are by no means decisive, many substances 
throwing down merely a white precipitate. The best method 
therefore, to detect its presence, is to have recourse to dis- 
tillation, in the manner described for arsenic, only that more 
heat is required for the zinc. This method is as follows : 

Assay of Zinc ores. 

The ore in the first place, is to be roasted with a gentle 
heat. If the heat is carried to redness, the metal will be 
sublimed ; the roasting is only intended to get rid of the 
sulphur and arsenic. After roasting, the ore must be reduced 
to fine powder, and mixed with lamb-black, or charcoal 
powder, and introduced into a green glass retort, and ex- 
posed to a red heat. The metal will rise by sublimation, 
and will be condensed in the neck of the retort, which must 
be loosely stopped, or dipped into a snail quantity of water. 
The weight of the metal may be known by weighing the ore 
and charcoal, both before and after the process. 

Analysis of Zinc ores. 

Process 1. Reduce a given weight to fine powder, and 
as some varieties are hydrates, submit to the temperature of 
boiling oil, or mercury ; this will drive off the water, the 
loss of which must be estimated. 

Process 2. Digest the ore without heat, for two or three 
days, in dilute nitro-muriatic acid ; if any caloric is gene- 
rated in the process, it should be kept down by immersing 
the vessel containing it in cold water ; stir the mixture occa- 
sionally with a glass rod, and pour off the clear liquor ; 
repeat the process of immersion, and well wash with hot 
water. The residue after this will be sulphur and silex ; 
separate by burning over the flame of a spirit lamp. Esti- 
mate the quantity of sulphur thus lost. 

Process 3. Examine the residue, supposed to be silex ; 
it may have a portion of sulphateof lead intermixed ; if this 
is the case, digest the whole in sulphuric acid ; this v/ill take 
up the lead, which is to be separated from the undissolved 
silex, and the former may be decomposed at a boiling tern- 



374 ANALYSIS OF METALLIC SUBSTANCES. 

perature in a solution of carbonate of potash. Carbonate 
of lead will fall, which should be collected, dried, and 
reduced to the metallic state. To ascertain the quantity of 
sulphur acidified by the nitric acid, and which was combined 
with the lead, but now with the potash, note the difference 
in the weight of the residues, before and after digestion with 
the sulphuric acid ; this will give the quantity of sulphate 
of lead, from which the equivalent quantities of acid and 
lead may be estimated. 

Process 4. The solution. No. 1, may now be tested for 
any free sulphuric acid, and acetate of barytes added, until 
no further precipitation ; this is to be collected, dried, and 
its equivalent of sulphur obtained and added to the former 
quantities ; this method will give the whole of the sulphur 
contained in the ore. 

Process 5. Or, the residual solution may be tested for 
lead, and, if it contains any, which will be the case if any 
sulphate of this metal was found in the residue, it may be 
thrown down by the sulphate of soda. 

Process 6. Test a drop of the liquor with caustic am- 
monia, and if a blue tinge is perceptible, it contains copper, 
which is to be throwai down by inserting into the acid solu- 
tion, a clean plate of iron, of known weight, as before 
mentioned. 

Process 7. Decompose the solution now holding zinc 
and iron, by carbonate of soda ; the carbonate of zinc, and 
oxide of iron, will be thrown down. Digest the precipitate 
in ammonia, the zinc will be dissolved, while the iron re- 
mains, and which may be reduced to the magnetic state by 
heating in a crucible with charcoal. 

Process 8. The ammonical solution may now be slight- 
ly super saturated with muriatic acid, and carbonate of soda 
added ; the carbonate of zinc will thus be obtained pure, 
and may be brought to the metallic state with a little char- 
coal, or black flux in a retort, or close crucible, heated to 
redness. — Joyce's Chemical Mineralogy, 

Reduction. 

The method of reducing the ores of zinc, is said to have 
been introduced into Europe from China, and that a person 
was sent to that country expressly for the purpose of obtain- 
ing the secret. For this purpose, the ore is broken into 
small pieces and submitted to a gentle heat in a reverberatory 



ANALYSIS OF METALLIC SUBSTANCES. 375 

furnace until the carbonic acid, sulphur, and other volatile 
substances, are driven off. This being done, the ore is re- 
moved and placed in large jars made of clay, on which air- 
tight covers are luted. Each jar has an iron pipe which 
passes down through the floor of the furnace, and dips into 
water. The furnace is of sufficient length to contain eight 
or ten of these jars. The jars being filled with ore, and 
the covers luted on, a fire is kindled in the furnace, the heat 
of which, raises the zinc by sublimation, and passing 
through the open pipes, it falls down, and is condensed in 
the metallic form, in the water below. The whole process, 
therefore, is merely a dry distillation. 

Zinc is a cheap and abundant metal. It is not only em- 
ployed in the form of sheets to cover the roofs of buildings, 
and other purposes, but also forms a component part of 
brass, one of the most useful of alloys. In making this 
composition, metallic zinc is not employed, since the heat 
necessary to melt the copper, would raise the zinc by sub- 
limation, and drive it away without effecting the object. 
The copper, therefore, in sheets, is placed between layers 
of calamine, (native carbonate of zinc,) in melting pots, and 
on the application of fire, the zinc sublimes from the ore, 
and combines with the copper, now at a red heat, the 
whole afterwards running down to the bottom of the pot, in 
the state of brass. 

It is a curious fact, that brass was known and employed 
in the arts, for a long time before it was even suspected 
that any such metal as zinc existed. It was known by ex- 
perience, that a certain earth, as it was thought, called 
Calamine, when heated with copper, changed that metal to 
a yellow color, and added considerably to its weight. But 
the ancient manufacturers of brass, it appears, never had a 
thought that the earth they employed was the ore of a metal, 
until the metal itself happened by accident to be produced. 

Iron. 

Thrs metal, in one form or another, is much more uni- 
versally diffused than any other, there being no minerali- 
zing substance with which it is not found in combination. 
The ores of iron, are, therefore, very numerous. For a 
description of the forms, colors, and composition of these 
ores, the author must refer the student to his *' Introduction 
to Mineralogy," where the distinctive characters, and defi- 



376 ANALYSIS OF METALLIC SUBSTANCES. 

nite analysis of each species is given. The general com- 
position of the principal species of iron ore, are the follow- 
ing : 

Native iron, Iron, lead and copper. 

Meteoric iron, Iron and nickel. 

Arseniate of iron, Iron, oxygen, and arsenic. 

Sulphuret of iron, Iron and sulphur. 

Oxide of iron. Iron and oxygen. 

Red iron ore, Iron, oxygen, silex and lime. 

Brown iron ore, Iron, oxygen, manganese and silex. 

Bog iron ore. Iron, oxygen, clay and manganese. 

Specular oxide of iron. Iron and oxygen. 

Spathose iron ore. Iron oxygen, and carbonic acid. 

Phosphate of iron, Iron and phosphoric acid. 

Chromate of iron, Iron and chromic acid. 

These are the principal ores of iron, though the list is 
far from containing the names of all the varieties known 
and enumerated. The ores of iron which furnish most of 
the metal, are the oxides, and the bog ore. 

Action of the blowpipe on Iron ores. 

Several of the ores of iron are magnetic in their native 
states, and this in general may be considered a sufficient 
test of the presence of the metal. These ores contain at 
least some particles of iron in the native state. The oxides 
of iron do not move the magnet, until submitted to the ac- 
tion of the blowpipe, when most of them, if this is done in 
contact with charcoal, or some other combustible matter, 
become distinctly magnetic. Some of these ores, after a 
long application of the heat, are reduced to a sort of cast 
iron, but more generally they form a shapeless slag, of a 
black color, which has no other indication of iron, than 
that of being lifted by the magnet. 

Tests for Iron. 

Infusion of galls. Black precipitate. 

Ferro-prussiate of potash, Blue do. 
Sulphuretted hydrogen, Black do. 
The most ready test for iron, in any saturated, or dilute 
solution, is 'mfusion of galls, or a little piece of the nutgall 



ANALYSIS OF METALLIC SUBSTANCES. 377 

itself, suspended in the solution. In either case, a dark 
precipitate will gradually fall. 

Assay of Iron ores* 

Before attempting the assay, the ore should be roasted 
with a strong red heat, as long as any vapor, or sroell ari- 
ses. After this, two parts of the mineral are to be inti- 
mately mixed by trituration, with one of fluor spar, one of 
charcoal* and four of common salt, by weight* This mix- 
ture is to be put into a covered crucible, and exposed to a 
white heat for an hour after which, if the operation has 
been well performed, a button of cast iron will be found at 
the bottom of the crucible, and by which the per centage of 
metal in the ore may be found. 

If the ore contains much stoney matter, one part of black 
flux should be added to the above mixture. The common 
salt, and fluor spar in the above process, act as fluxes, while 
the charcoal absorbs the oxygen from the metal. 

Analysis of Iron ores. 

There is, in general, no great diflSculty in the analysis of 
the ores of iron. The pitchy ore, which is a sulphuric oxide 
of the metal, often containing manganese, may be treated 
as follows t 

Process 1. Pulverize the ore, and introduce a given 
weight into a flask, and pour on such a quantity of dilute 
muriatic acid as will take up every thing soluble, then filter, 
and wash the residue with water. 

Process 2. Add together the solution and washings of 
the above process, and drop in solution of muriate of ba- 
rytes until no further precipitation takes place. The pre- 
cipitate will be sulphate of barytes, formed by the mutual 
decovnposition of the muriate of barytes added, and the sul- 
phate of iron in the solution. To separate these, the solu- 
tion must again be filtered, washed, dried, and weighed, and 
the quantity of sulphuric acid in the sulphate of barytes, es- 
timated by the scale of chemical equivalents. 

Process 3. The filtered liquor now contains the iron and 
manganese. This is to be concentrated by evaporation, 
and a small quantity of nitric acid added, in order to render 
the iron a peroxide, and make it more readily separable. 
Caustic ammonia in solution must now be poured in, in 
excess, by which the iron will be precipitated, and can be 

32* 



3t8 ANALVcJlS 01 IviLTALLiC b l-BSTAi\CES. 

obtained by decanting the liquid, after which it may bo 
brought to the magnetic state, by heating in a crucible, with 
resin, or linseed oil. ' 

Process 4. The excess of ammonia must be driven off 
by heat, after which the oxide of manganese will fall, 
and after being dried, its weight found. In this manner 
the weight of iron in a given quantity of the ore is deter- 
mined. 

In cases where much silexis mixed with the ore, as in the 
specular and magnetic oxides, where the acids have little 
effect in their native state, these are to the fluxed with three 
or four times their weight of potash, after which the muriatic 
acid will readily effect a solution of the whole of the iron, 
and which is then to be precipitated with ammonia, and after 
drying, brought to the magnetic state as above directed. 

Reduction of the ores of Iron, 

The ore is broken into small pieces by the aid of the 
stamping mill, which consists of several beams of wood, 
shod with iron, which are alternately lifted up, and let fall 
on the ore contained in a strong box. The machinery for 
this purpose is moved by means of w^ater or steam. 

After the ore is broken, it is roasted to drive off the sul- 
phur and other volatile matters. It is then transferred to 
the smelting furnace, where it is mixed with charcoal and 
lime, or sometimes with oyster shells, and melted, and thus 
becomes impure cast iron, or when cast into moulds, is 
known by the name oi pig iron. 

The pig iron is next broken in pieces and removed to 
another furnace where, in England, it undergoes the process 
called puddling, for which, many years ago, a patent was 
obtained. This operation consists in placing the broken 
pigs in a reverberatory furnace, and when in fusion, stirring 
it witli iron bars, so that every portion may be exposed io 
the air and flame. After a time the mass swells, emits a 
blue flame, and gradually becomes tenacious and less fusible, 
and at length is granulated or converted into small separate 
pieces. The fire is then urged so that these particles again 
agglutinate, and at a welding heat are again brought into 
masses. In this state of intense heat, the masses are passed 
in succession between iron rollers, by which a large quantity 
of extraneous matter is pressed out, and the iron becomes 



ANALYSIS OF METALLIC SUBSTANCES. 379 

malleable. The sheets thus formed are then cut into bars, 
and again heated and hammered by means of a great mass 
of iron lifted by machinery, and thus become the malleable 
iron of commerce. For a detailed account of the processes 
of working iron, the reader is referred to " Aikin's Diction- 
ary of Chemistry," and for the construction of furnaces for 
the smelting of this and other metals, to " Gray's Operative 
Chemist." 

Chrojne, 

The color of this metal is between tin white and steel 
gray. It is obtained from the chromate of iron which is 
found native in various places. The metal is of no use in 
the arts, but its salts, especially the chromate of lead is em- 
ployed extensively as a pigment. 

The ores of chrome are the following : 

Oxide of chrome. Chrome and oxygen. 

Chromate of iron. Chromic acid and iron. 

Chromate of lead, Chromic acid and lead. 

Action of the Blowpipe. 

The green color of the oxide of chrome is changed to yel- 
low by the blowpipe. With borax it forms a green glass. 
The chromate of iron is infusible alone, but w^ith borax fuses 
into a bead of a rich and lively green. The native chromate 
of lead, also forms a green bead with borax. 

Tests for Chrome, 

The solutions of chrome are readily and strikingly distin- 
guished by the fine yellow precipitate they form with nitrate 
of lead, which when dried, is known under the name of 
chrome yellow. With other nitrates the solutions of chrome 
form precipitates as follows. 

Nitrate of mercury. Rich cinnabar precipitate. 

Nitrate of silver. Carmine, changing to purple. 

Nitrate of copper. Chestnut precipitate. 

Assay of the ores of Chrome, 

As metallic chrome is useless, and difficult to obtain on 
account of the intense heat necessary for its fusion, all that 



380 ANALYSIS OF METALLIC SlJBStAKCJESi 

is necessary in the assay, is to ascertain the quantity of oxide 
the ore contains. 

Process 1. Reduce a known portion of the chromate of 
iron, to a fine powder, and mix it with half its weight of 
nitre, and expose to a red heat in a crucible, for an hour, 
or until all the nitrous gas is expelled. By this process the 
chromic acid is absorbed by the potash of the nitre, and a 
chromate of potash is formed, while the oxide of iron re- 
mains free. 

Process 2. Dissolve the chromate of potash with hot 
water, and separate the oxide by filtering through clo'h. 
Test the liquor with sulphuric acid, when if there arise the 
fumes of nitric acid, it shows that undecomposed nitre still 
remains, and probably chromic acid, and chromate of iron 
also. If it contains the latter, the solution must be evapo- 
rated to dryness, again mixed with nitre and fused, and the 
chromate of potash dissolved out as before, and this liquor 
added to the former. 

Process 3» The whole liquid must now be saturated with 
nitric acid, which generally throws down some earthy matter ; 
filter this, and pour in solution of nitrate of mercury until 
no further precipitation takes place ; throw the whole on a 
paper filter, collect and dry the red chromate of mercury 
thus obtained. 

Process 4. In order to obtain the oxide of chrome, the 
chromate of mercury obtained above must be placed in a 
retort, or muffle, and a moderate heat applied ; the mercury 
will thus be expelled, and the green oxide of chrome will 
remain, from which can be estimated the per centage of chro- 
mate of iron in the ore. 

Analysis of the Chromate of Lead, 

The color of the native chromate of lead is various tints 
of red, often very beautiful. Its composition is oxide of lead 
64, chromic acid 36. 

Process 1. A given weight of the powdered ore is placed 
in a clean iron, or unglazed earthen vessel, and on it poured 
a solution of 3 or 4 parts of carbonate of potash in water; 
boil with a gentle heat until the chromate of lead is decom- 
posed, when there will be in solution, carbonate of lead and 
chromate of potash : pour the wdiole on a filter, and having 
washed, dry the residuum, which will be carbonate of lead. 
Should any yellowness remain, this powder must again be 



ANALYSIS OF METALLIC SUBSTANCES. 381 

boiled with potash as before, and the whole added together, 
filtered, and reduced to metallic lead by fusion with char- 
coal or black flux. 

Process 2. The chromic acid may be readily obtained 
from the remaining solution, thus, — Acidulate the solution 
with nitric acid, and then add muriate of barytes until no 
further precipitate falls ; collect the chromate of barytes 
thus formed on a filter. 

Process 3. The chromate of barytes of the last process 
is to be digested in dilute nitric acid, in quantity just suffi- 
cient to dissolve it ; then add sulphuric acid, and the sul- 
phate of barytes w411 be precipitated, leaving the chromic 
acid in solution. 

Process 4. The solution must now be evaporated, when 
crystals of red chromic acid will form, the w^eight of which 
will show by estimation the per centage of the chromate of 
lead the ore contained. 

Uranium. 

In the metallic state uranium is of no use, but some of its 
oxides are used as a coloring matter for porcelain. Its ores 
are rare, and generally occur only in small quantities. 

Black oxide of uranium, { Oxide of uranium, with lead, 
Green oxide of uranium, ( copper, iron, and silex. 

Action of the Blowpipe, 

The ores of uranium are infusible alone, but with borax 
they form a dark slag. They dissolve in nitric acid, with 
emission of nitrous fumes. 

Tests for Uranium. 
The salts of this metal are yellow, or greenish yellow. 

Alkalies, Yellow precipitate. 

Hydro-sulphate of ammonia. Dark brown do. 

Ferro-cyanate of potash, Fine brown do. 

Hydriodic acid, Reddish yellow do. 

Analysis. 

Process 1. The species, black oxide of uranium, may 
be thus analysed. Digest a given quantity of the ore finely 



382 ANALYSIS OF METALLIC SUBSTANCES. 

powdered, with four or five parts of dilute nitric acid, until 
all action ceases, and the addition of more acid produces no 
effect ; sulphur and silica will remain after filtration, and 
may be separated by burning away the sulphur, and the 
weights of each ascertained. 

Process 2. To the filtered solution, add sulphate of soda, 
which will precipitate the lead in form of a sulphate ; col- 
lect and dry this, and estimate the quantity, or reduce to the 
metallic state with charcoal. 

Process 3. The solution now remaining is to be mixed- 
with caustic potash, when a precipitate will fall, which after 
being separated by filtration, must be digested in a solution 
of caustic ammonia, by which the copper will be dissolved, 
and may be obtained and weighed, by slightly supersatu- 
rating the ammoniacal solution with an acid, and then im- 
mersing a slip of clean iron or zinc, as formerly directed 
with respect to copper. 

Process 4. The oxides of uranium and iron now remain 
in the liquid, to which must be added some fresh nitric acid 
in order to effect their entire solution, after which, caustic 
ammonia is to be poured in, which will precipitate the ox- 
ides of uranium and iron. These are to be collected by 
filtration, and washed and dried, mixed with a little muriate 
of ammonia, and thrown by small parcels at a time into a 
red hot crucible, by which, according to Mr. Joyce, the iron 
will be removed, while the oxide of uranium will remain. 

Or, the mixed oxides may be boiled in a solution of bi- 
carbonate of potash, which will take up the oxide of ura- 
nium, and leave the iron; to obtain the first, supersaturate 
the solution with muriatic acid, and precipitate with caustic 
ammonia ; or, the iron may be precipitated by a slip of 
zinc, and the mixed oxides of uranium and zinc obtained 
by precipitation with caustic potash, and treated with pure 
ammonia, which will dissolve the zinc, and leave the urani- 
um in solution. 

The metal may be obtained by evaporating the above 
liquid, and heating the oxide intensly with charcoal powder. 
It is a brittle metal of a gray color. 

Platinum. 

This metal is found in the form of small grains, resem- 
bling in color and appearance coarse iron filings, only that 
their sharp angles are rounded. Sometimes masees are 



ANALYSIS OF METALLIC SUBSTANCES. 383 

found of the size of a filbert, but these are very rare, the 
medium size being less than that of flax seed. These grains 
are however never pure platinum, but generally contain 
palladium, and rhodium, iridium, and osmium, and some- 
times, gold, silver, lead, and titanium. 

These grains contain from 55 to 60 per cent, of platinum. 
They are perfectly infusible by all common means, but in 
small quantities yield to the compound blov^-pipe. The 
alloys of platinum must therefore be analyzed in the moist 
way, that is, by means of acids, and not by heat. 

Tests for Platinum. 

The solutions of this metal in nitro-muriatic acid, it being 
insoluble in any other, are of a brownish yellow. 

Muriate of ammonia, Yellow precipitate, 
Muriate of tin, Bright red do. 

Alkalies, Yellow do. 

Assay of Platinum, 

Process 1. Digest a given quantity of grain platina, say 
100 grains, in a retort, with 10 times its weight of aquaregia 
consisting of four parts of muriatic, with one part of nitric 
acid ; apply the heat of a lamp until one half the acid 
passes over into the receiver ; decant the fluid remaining 
in the retort, and repeat the process with a fresh quantity 
of acid as before, and if necessary a third time. There 
will now appear a dark colored powder at the bottom of the 
retort, being the insoluble matter the metal contained, while 
the platina will be in solution. This must now be thrown 
on a filter, and washed with pure w^ater. 

Process 2. The solution of platina, which is of a brown 
color must next be treated with solution of muriate of am- 
monia, which will precipitate the metal in form of a yellow 
oxide, and this must be collected, washed and dried. 

Process 3. The dried precipitate of the last process, is 
to be heated in a crucible until all fumes cease, when there 
will remain a spongy mass of platina, the weight of which 
will show the percentage of the metal in the quantity as- 
sayed. Thus of the 100 grains, if 55 grains remain, it 
shows 55 per cent., the rest being oxygen. 

This, it will be seen, does not show the exact analysis of 
the metal, but only the quantity of platina it contained. Ir 



384 ANALYSIS OF METALLIC SUBSTANCES. 

order to obtain the number, and precise quantity of the dif- 
ferent substances which grain platina contains, requires a 
much more extended analysis, and which can only be made 
by those who have had much experience, and possess great 
skill in chemical manipulations. It is therefore hardly 
necessary to describe here, the various and complicated 
processes by which it is done. 

Malleable Platina. 

Platina, being the most infusible of the metals, and at 
the same time not oxydable by exposure, or by heat, and 
being soluble only in nitro-muriatic acid, it is therefore one 
of the most perfect of metallic substances. For many uses 
in the arts, it is superior to gold itself, and for others, as 
chemical vessels, no other substance can take its place. It 
would therefore come into general use for a great variety 
of purposes, did not its high price keep it among the more 
rare and precious metals. The quantity in vv^hich this metal 
exists, nor the difficulty of obtaining it, are the reasons for 
this scarcity, but the labor and expense of purifying, so as 
to render it a malleable metal. Like iron, it can be welded, 
which property exists in no other metals, but for this pur- 
pose it passes through a variety of processes, of which the 
following are descriptions. 

First. Precipitate the platina from its solution, by the 
muriate of ammonia, and reduce it by heat in a crucible, to 
the spongy metallic texture, the several processes of doing 
which, are already described above, under the article " as- 
say," and which it is not necessary here to repeat. 

Second, To one part of this spongy metal, add two parts 
of mercury, and with a pestle amalgamate them in a glass 
mortar. This is readily done, the two metals having a 
strong affinity to each other. Where considerable quan- 
tities are to be amalgamated, small parcels of each are to 
be done at a time, the best method of conducting it being 
to combine about two drachmas of mercury to three of the 
platina, and having made the union perfect, by rubbing 
with the pestle, add to this, small quantities of each, until 
the whole is united. 

Third. When the whole quantity is amalgamated, it is 
to be compressed into tubes of hard wood, by means of an 
iron screw, the pressure of Avhich is against a cylinder of 
wood, adapted to the bore of the tube. By this means the 



ANALYSIS OF METALIC SUBSTANCES. 385 

mercury of the amalgam is forced out, and the particles of 
the platina are brought together so as to make a solid mass. 
Fourth. After the metal has remained under pressure as 
above described for two or three hours, place the tube of 
wood containing the platina on charcoal, in a smith's forge, 
or in a crucible lined with charcoal, and after the wood is 
burned away, urge the fire to the highest possible degree of 
whiteness, after which, the cylinder of platina may be taken 
out of the lire and while white with heat, hammered light- 
ly for a moment, and then returned to the lire again, pre- 
paratory to the repetition of the same process. The metal 
now becomes solid, and lit to be forged, or drawn into wire. 
If however, has not been well purified from the osmium, 
iridium, and other metals which crude platina usually con- 
tains, it will break under the hammer, and never can be 
made malleable. The only remedy for this evil, is to re- 
dissolve the whole in nitro-muriatic acid, and repeat the 
several processes as already described. 

Molybdenum. 

This metal is obtained in its pure state, with considerable 
difficulty, and when thus obtained, is not applied to any 
useful purpose. Its ores are few in number and exist only 
in small quantities at a place. 

Sulphuret of molybdena, Molybdena and sulphur. 
Oxide of molybdena, Molybdena and oxygen. 

Molybdate of lead, Molybdic acid and lead. 

Action of the Blowpipe. 

When the native sulphuret of molybdena is exposed to 
the action of the blowpipe, sulphurous vapors, in the first 
place are emitted, and afterwards, if the heat be urged, 
white fumes arise, being an oxide of the metal. By means 
of nitric acid, this metal is converted into molybdic acid. 

Tests of solutions of MoUhdcna. 

The molybdic acid forms soluble salts with soda, potas.i, 
and ammonia. The solution of molybdic acid, in sulphu- 
ric acid, is of a blue color when cold, changing to white 
when heated, and to blue again Avhen cooled. The molyb- 

33 



ANALYSIS OF METALLIC SUBSTANCES. 

dates of potash and soda, give precipitates with almost every 
metalic solution. 

Muriate of gold, White powder, 

Muriate of mercury, White do. 

Muriate of tin, Blue do. 

Muriate of cobalt. Rose colored do. 

Assay of the ores of Molybdena. 

The method of assaying the sulphuret of molybdena, is 
very simple. It is first digested in nitric acid with heat ; 
this will form molybdic acid, which will remain in solution, 
while the sulphur will be left behind. After filtration, the 
solution is to be evaporated to dryness, when molybdic acid 
will be the result. 

Manganese. 

The ores of this metal are quite common, and in some 
instances it is found in large quantities, though more fre- 
quently it occurs with the ores of other metals of which it 
forms a small portion. The following are the must common 
ores of manganese : 

-Di ^ ' 1 c ^ Manganese, oxygen 

Black oxide oi manganese, < ^^ x 

° ' ( and water. 

cj-r ./» -1 r ( Manoranese, oxygen 

bihcilerous oxide of manganese, < i -i '^ ^ 

^ ( and silex, 

Sulpherct of manganese. Manganese and sulphur. 

t3i . r ^ Phosphoric acid and 

Fhosporate oi mano^anese, < ^ 

^ I manganese. 

Action of the blowpipe on manganese. 

Heat alone on the oxides of this metal, produces little ef- 
fect. With borax they form a beautiful violet colored 
glass, which is always a good test of the presence of this 
metal. 

When the metal is in solution with muriatic acid, the 
alkalies throw down a white precipitate, which turns black 
on exposure to the air. 

Assay. 

Process 1. Dissolve the black oxide in muriatic acid, 
which will also take up the iron with which it is usually 



ANALYSIS OF METALLIC SUBSTANCES. 387 

mixed ; add caustic ammonia in excess ; this will throw 
down the oxide of iron, leaving the manganese in solution, 
which is then to be obtained, by evaporating to dryness, 
and exposure to a red heat. 

Process 2. The pure oxide thus obtained is to be mixed 
into a paste with linseed oil, and a little charcoal, and sub- 
mitted in a crucible to the most violent heat that can be 
raised, for an hour or more, when if the experiment is well 
performed, a button of the metal will be found at the bot- 
tom. This is of an iron grey color, is magnetic, hard and 
brittle, and soon tarnishes on exposure to the air. Metallic 
manganese has not been applied to any use. It is, however, 
of considerable consequence in the form of the native ox- 
ide, as being the substance from which oxygen is obtained 
for bleaching, and other purposes. 

Vanadium* 

This was discovered in 1830, and therefore is not con- 
tained in the catalogue of metals in the preceding volume. 
Its name is from Yanadis, a Scandinavian deity, and its dis- 
coverer, Seftstrom, who found it in the ores of iron from Ta- 
berg, in Sweden, and in the slag of reduced ore from that lo- 
cality. The same metal was soon after found by Mr. John- 
ston, of Durham, Eng. in a lead ore from Wanlock-head ; and 
by Del Rio, also, in a lead ore from Zemapan, in Mexico. 
Thus did these three chemists find this metal at about the 
same time, without the knowledge of each other, and in 
widely different parts of the world. The merit is, however, 
conceded to Prof. Seftstrom, as being the first discoverer. 

Analysis of Vanadium, 

j Vanadium is most readily obtained from the vanadiate of 

I lead, which is found native. 

Process 1. Dissolve the ore in nitric acid, and pass 
through the solution a current of sulphuretted hydrogen, 

I which will precipitate the lead, and any arsenic it may con- 

\ tain. Filtrate the blue solution which remains, and evapo- 

\ rate it to dryness. 

Process 2. Dissolve the above residue in liquid ammo- 
nia, and drop into this solution pieces of muriate of ammo- 
nia, in quantity more than is dissolved. This will throw 

, down the vanadiate of ammonia in the form of a white 

j powder. This powder is then washed with a solution of 



388 ANALYSIS OF METALLIC SUBSTANCES. 

muriate of ammonia, in which it is insoluble, and afterwards 
with good alcohol. 

Process 3. The vanadiate of ammonia is decomposed 
by heating it in a platinum crucible to redness, by which 
vanadic acid is produced. This acid is then reduced to 
the metallic state by the action of potassium, which at a 
moderate heat absorbs the oxygen, and leaves vanadium in 
a pulverulent form. 

This metal has a metallic, silvery appearance, conducts 
electricity, is extremely brittle, and is not acted upon by 
air or water at common temperature. At a dull red heat, 
it absorbs oxygen from the atmosphere, and takes fire, 
leaving behind a black oxide. 

Vanadium and Oxygen, 

There are three compounds of this metal with oxygen, 
two oxides and an acid. 

Protoxide of vanadium. This is composed of 68 parts 
of vanadium, and 8 of oxygen. It is a black substance, 
which is extremely infusible, and strongly electro-negative, 
in relation to zinc. 

Deutoxide of vanadium. When 10 parts of protoxide of 
vanadium, and 12 of vanadic acid, are intimately mixed, 
and heated in an exhausted receiver, or in a vessel of car- 
bonic acid, a black compound is obtained, which is insolu- 
ble in water, and which consists of 68 of vanadium, and 16 
of oxygen. 

Vanadic acid. When vanadiate of ammonia is heated, 
vanadic acid remains as above described. When fused, 
this acid is red, but when in powder it is brown. It under- 
goes no changes by heat when all combustible agents are 
absent, but when such agents are present, a portion of oxy- 
gen is absorbed, and it passes into the state of an oxide. 
This acid is tasteless, insoluble in alcohol, and nearly so in 
water. 

The equivalent of vanadic acid is 92 ; it consists of 

1 proportion vanadium, 68 
3 proportions oxygen, 24 

92 



ANALYSIS OF METALLIC SUBSTANCES. 389 

Vanadiates. 

The compounds of vanadic acid with salifiable bases, arc 
generally yellow, or arange, but they are sometimes color- 
less, without any apparent change of composition. Vana- 
dic acid dissolves the deutoxide of vanadium, and forms 
with it compounds, which in solution with water, changes 
color from blue to green, and then yellow, and finally red, 
in proportion to its acidification. 

The salts of this metal are best obtained by the action of 
the respective acids upon the hydrated deutoxide. They 
are blue, and afford a gray precipitate with alkalies, which 
exposed to the air becomes red. The nitrate of vanadium, 
which is at first blue, becomes red during evaporation, from 
the formation of vanadic acid. 

Chlorides of Vanadium. 

When deutoxide of vanadium is digested in muriatic 
acid, a brown compound is obtained, which appears to be a 
bichloride. When dry chlorine is passed over a red-heated 
mixture of protoxide of vanadium and charcoal, in a glass 
tube, a yellow liquid is obtained, which when acted upon 
by water, yields muriatic, and vanadic acids. This contains 
three portions of chlorine, and is therefore a terchloride of 
vanadium. 

Sulphurets of Vanadium. 

By passing a current of sulphuretted hydrogen over the 
deutoxide, heated to redness, a bisulphuret of vanadium is 
obtained. The same compound is formed when sulphate 
of ammonia is mixed with a solution of salt of vanadium, 
till the precipitate first formed is re-dissolved, and then de- 
composing the deep purple solution by sulphuric, or muri- 
atic acid ; a brown bisulphuret subsides, which becomes 
black when dried. 

33* 



390 MISCELLANEOUS FACTS 

PART VI. 

Miscellaneous Facts and Experiments. 

Some of these are new discoveries, while others are such 
as hardly can be included under any chemical arange- 
ment; and others, again, though pertaining to subjects 
treated of in the body of the work, are perhaps more ad- 
vantageously learned here, than in any connection. 

Wine. 

Wine^ properly so called, is exclusively derived from the 
fermented juice of the grape. The principal substances 
in this juice, are sugar, gum, gluten, and bitartrate of pot* 
ash. 

This liquor readily passes through the vinous fermenta- 
tion, without any addition, or spontaneously, at tempera- 
tures between 60° and 80"". After fermentation, the spe- 
cific gravity of the liquid is diminished, its flavor is entire- 
ly changed, and it is found to contain exciting or intoxica- 
ting qualities, from the formation of alcohol, of which, be- 
fore this process, it contained not the slightest trace. Al- 
cohol is, therefore, the product, or creation, of the vinous 
fermentation, 

A question naturally suggests itself here, says Prof. 
Brande, why the juice of the grape does not ferment in the 
fruit itself? We know that ripe grapes, even when cut 
from the vine, exhibit no such tendency ; they dry up, and 
shrivel, becoming raisins, but never fermenting, so long as 
the skin is entire. It was once supposed that this arose 
from the gluten, or ferment being in distinct vesicles, or 
cells, from those containing the saccharine juice, and that 
consequently fermentation could not ensue, till the fruit 
was mashed, or broken so as to mix these ingredients. But 
Gay Lussac found, that when grapes were bruised, and 
carefully excluded from the air, no change ensued ; but 
that even a momentary exposure of the pulp to the air, or 
oxygen gas, was enough to communicate to it the power of 
fermentation. This seems to arise from some recondite ac- 
tion of oxygen on the glutinous principle of the grape, by 
absorbing which, it acquires the properties belonging to 
yeast. It is curious how perfectly the exclusion of air is 
provided for by the natural texture of the grape skin, which 
does not allow its ingress in the smallest degree, though it 



AND EXPERIMENTS. 991 

admits of the transpiration of the aqueous vapor, as is 
shoAvn by the desiccation of the fruit. 

It is well known that there is a great variety of wines, 
which differ from each other in color, flavor, and strength, 
as well as in price. These differences depend on various 
circumstances, as purity, scarcity, fame, and real qualities, 
for in the latter respect, there are certainly great and mate- 
rial difl!erences. Some wines will not keep through the hot 
season, or in a hot climate, without such an addition of 
brandy as to injure, or spoil the original flavor, and purity 
of the liquor ; others have a fine flavor, and have naturally 
sufficient alcohol to preserve them in any, or all parts of 
the world. 



Alcohol. 

All wines contain more or less alcohol, which as above 
stated, is the product of the vinous fermentation. It was 
formerly denied, however, that the alcohol pre-existed in the 
wine, but that it was the product of distillation. Its ele- 
ments, it was urged, did exist in the wine, but that they 
were brought together to form the alcohol by the heat of 
distillation, and then raised and separated from the wine 
by a continuance of the process. The inference of this be- 
lief has been, that he who drank wine, did not of course 
take any portion of alcohol, this depending on the fact, 
whether any had been added to the wine. But that wine, 
and in truth, all fermented liquors contain alcohol, and that 
this is the product of fermentation, is shown by the fact, 
that the juice of the grape, or other fermentative liquors, 
contains no alcohol until after having passed through that 
process, and that after this, alcohol can be separated from 
it without distillation, or the use of heat in any way. 

Method of obtaining Alcohol without distillation. 

For this purpose, either wine, cider, or beer may be se- 
lected, the experimenter being satisfied, that no alcohol has 
been added to the liquor, to be used in the experiment. 

A glass tube, say half an inch in diameter, and two feet 
long, being procured, fill it about half full of the liquor to 
be tried. Then drop into the liquor, pieces of carbonate of 
potash, which has previously been well dried by heat. Con- 
tinue this until all the water has been taken up and incor- 



392 



MISCELLANKOtJS FACTS 



porated with the alkali, when the alcohol will gradually 
rise to the upper portion of the tube, and stand in a distinct 
stratum on the other contents. By graduating the tube 
into 100 equal parts, by pasting on its outside a strip ot 
paper thus divided, the percentage of the alcohol in differ- 
ent kinds of wine may at once be determined. It is diffi- 
cult, however, if not impossible, to extract all the alcohol 
by this method, since the quantity of alkali necessary to 
absorb all the water^ tends to thicken the liquid, and thus 
prevent some of the particles of alcohol from rising through 
it. While therefore, this method serves to show beyond 
all doubt, that the alcohol exists in the wine before distilla- 
tion ; yet when the experimenter designs to obtain the 
whole quantity of alcohol in any liquid, the only sure 
method is, after saturating the wine, or other beverage with 
lime, or potash, to use a gentle heat ; and a long necked 
glass retort, reaching a good distance into the receiver, is 
the best apparatus. 

Proportions of Alcohol in different Wines, 
The following Table, from Brande's Manual of Chemis- 
try, exhibits the proportion of alcohol, specific quantity of 
0.825, at 60°, by measure, existing in 100 parts of the sev- 
eral kinds of wine and other liquors. 

Per cent, of Alcohol by measure. 



1. 


Lissa, • 


- 26.47 




do. - - - 


. 23.93 




do. - 


24.35 




do. (Sercial,) - 


21.40 




Average, 


- 25.41 




do. - - - 
Average, - 


- 19.24 
22.27 


2. 


Raisin wine, 


26.40 










do. - - - 
do. - 

Average, 


- 25.77 
23.20 

- 25.12 


6. 


Currant wine, 


- 20.55 




7. 


Sherry, - 

do. - - - 


19.81 
. 19.83 


3. 


Marsala, 
do. - - - 
Average, - 


26.03 

. 25.05 

25.09 




do. - 

do. - - - 
Average, - 


18.79 

. 18.25 
19.17 


4. 


Port, - 


. 25.83 


8. 


Teneriffe, - 


- 19.79 




do. - 


24.29 


9. 


Colares, - 


19.75 




do, . - * 


- 23.71 


10. 


Lachryma Christia, 


- 19,70 




do. - 


23.39 


11. 


Constantia, white, 


19.75 




do. - - . 


- 22.30 


12. 


do. red, - 


- 18.92 




do. - - - 


21.40 


13. 


Lisbon, 


18.94 




do. . - - 


- 19.00 


14. 


Malaga, 


- 18.94 




Average, - 


22.96 


15. 


Bucellas, - 


18.49 




V ^_ 




1 16. 


Red Madeira, 


- 22.30 


5. 


Madeira, - ' 


- 24.42 




do. 


18.40 



AND EXPERIMENTS. 



393 





Average, 


- 20,35 




do. (old in cask,) - 
Average, - 


8,88 
12.08 


IT 


Cape Muschat, - 


18.25 








18. 


Cape Madeira, 


- 22 94 


35. 


Nice, - - - - 


14.63 




do. - - 


20.50 


36. 


Barsac, - - - 


13.86 




do. - 


- 18.11 


37. 


Tent, - . - - 


13,30 




Average, - 


20.51 


38. 


Charopagne, (still,) - 
do. (sparkling.) 


13.80 
12.80 


19. 


Grape wine, - 


- 18.11 




do. (red,) - 


12.56 


20. 


Calcavella, 


19.20 




do. do. - 


11.30 




do. - . - 


- 18.10 




Average, - 


12.61 




Average, - 


18.65 




a 5 




^1. Vidonia, - 
22 Alba Flora, - 

23. Malaga, - 

24. White Hermitage, 


- 19.25 

- 17.26 
17.26 

- 17.43 


39. 
40. 


Red Hermitage, - 
Yin de Grave, - 
do. - 

Average, - 


12.32 
13.94 
12.80 
13.37 


25. 


Rousillon, 


19.00 










do. - ' - - 


- 17.26 


41. 


Frontignac, (Rivesalte,) 


12.79 




Average, - 


18.13 


42. 


Cote Rotie, - 


12.32 






43. 


Gooseberry wine, 


11.84 


26. 


Claret, - 


- 17.11 


44. 


Orange wine, - 


11.26 




do. - 


16.32 


45. 


Tokay, 


9.88 




do. - - - 


- 14.08 


46. 


Elder wine, - - 


8.79 




do. - 


1291 


47. 


Cider, (highest average,) 


9.87 




Average, 


- 15,10 




do. (lowest,) - 


5.21 








48, 


Perry, (average,) 


7.25 


27. 


Zante, 


17,05 


49. 


Mead, - - - - 


7.32 


28. 


Malmsay Madeira, 


- 16.40 


50. 


Ale, (Burton,) - 


8.88 


29. 


Lunel, 


15.52 




do. (Edinburgh,) - 


6,20 


30. 


Sheraaz, 


- 15.52 




do. (Dorchester,) 


5.56 


31. 


Syracuse, - 


15.28 




Average, 


6,87 


32. 


Santerne, 


- 14.22 








33. 


Burgundy, 


16.60 


51. 


Brown stout, 


6.80 




do. - - - 


- 15,22 


52. 


London Porter, (average,) 


4.20 




do. 


14.53 


53. 


do. (small Beer,) - 


1.28 




do. - 


- 11.95 


54. 


Brandy, - - - 


53.39 




Average, - 


14.57 


55. 


Rum, - - - - 


53.68 








56. 


Gin, 


57.60 


34. 


Hock, - 


- 14.37 


57. 


Scotch Whiskey, - 


54.32 




do. . . 


13,00 


58. 


Irish do. - * - 


53.90 



" The wines, says Prof. Brande, employed in the experi- 
ments upon which the preceding table is founded, were se- 
lected with all possible caution as to purity and quality ; a 
given measure of each (saturated, when necessary, v/ith 
lime, or potassa,) was carefully distilled nearly to dryness, 
and the bulk of the distilled product was exactly made, 
equal to that of the original wine, by the addition of dis- 
tilled water. After 24 hours, its specific gravity was deter- 
mined, and thence the quantity of alcohol, by reference to 
Gilpin's Tables:' 



394 MISCELLANEOUS FACTS 

Combinations of Hydrogen, 

There are several combinations of hydrogen with vari- 
ous substances, and several names expressive of such com- 
pounds, some of which are new, and which therefore, we 
will explain at this place. 

Hydracids. 

The hydracids fire combinations of hydrogen with certain 
bases, which compound performs the part of an acid in the 
formation of salts. These acids and their salts are there- 
fore remarkable for the absence of oxygen, and the pre- 
sence of hydrogen. It was formerly supposed that oxygen 
was the universally acidifying principle, and hence its name, 
as already explained. But further investigations have shown 
that salts are formed without the presence of oxygen, hy- 
drogen in one sense, being the substitute for oxygen. 
These co'mpounds, therefore, are called salts of the hydra- 
cids, in order to distinguish them from the salts of the 
oxyacido, which contain oxygen, as the acidifying principle. 

The substances with which hydrogen unites to form acids, 
are chlorine, iodine, dromine, fluorine, selenium, sulphur, 
and cayanogen. These acids, according to the nomencla- 
ture formerly explained, form severally, hydrochloric, hy- 
dr iodic, hydrobromic, hydrofluoric, hydroselenic, hydrosul- 
phuric, and hydrocyanic acids. The hydrocyanic is the 
prussic acid, the hydrochloric, the muriatic, and the hy- 
drosulphuric, sulphuretted hydrogen ; to the others, there 
are no old, or common nam.es. 

The Salts which these acids form with alkaline or metal- 
lic bases, are hydro chlorates, hydriodates, hydrobromates, 
hydrofluorates, hydroseleniates, hydrosulphates, and hy- 
drocyanates. These names of course indicate the constit- 
uents of the several compounds to which they apply. 

Some of these salts are highly important and universally 
known, while others are worthy of notice only as chemical 
compounds. We shall here refer only to the former. 

The Hydrochlorate of Am.monia is the muriate of Am- 
monia, more commonly known under the name of sal am- 
moniac, 

Hydrochlorate of soda is the muriate of soda, or com- 
mon salt. 



AND EXPERIMENTS. 395 

The hydrocyanates^ or prussiates, have already been ex- 
plained. 

The hydroterrocyanates, are salts which were formerly 
called triple prussiates. They are combinations of hydro- 
gen, iron, and cyanogen, as the name indicates. 

The term hypo is prefixed to a number of acids and salts, 
to denote the first degree of oxygenation. Hypo means 
sub, or under, and is employed in cases where bodies are 
capable of combining with more than two proportions of 
oxygen. The nomenclature of the acids of sulphur form 
an example. These acids are four in number, depending 
on different degrees of oxygenation, and are termed 1, hypo- 
sulphurow5 acid ; 2, sulphurow^ acid, 3, hyposulphuric acid ; 
4, sulphur/c acid. When these several acids are combined 
with salifiable bases, the names of the salts thus formed, are 
hyposulphites, sulphites, hyposulphates, and sulphates. 

Experimental Illustrations. 

The following experiments are designed to illustrate, in 
a more familiar manner than we have heretofore done, a 
variety of subjects connected with Chemistry. Some of 
them are improved methods of arriving at results, which we 
have described other means of obtaining, while others are 
of recent invention, and have for their objects, results 
which this volume has not before pointed out any means of 
obtaining. 

Combination of Oxygen and Hydrogen, 

It has already been stated that when oxygen and hydrogen 
are burned together, the product is water. We have also 
pointed out a method of making this experiment, but the 
more simple and elegant plan of Prof. Mitscherlich of Ber- 
lin, is the following. 

The exact proportions in which these gase? combine to 
form water, are two of hydrogen and one of oxygen, and in 
consequence of the combination, the volume is diminished 
2000 times, that is, the water takes up 2000 times less space 
than did the gases. 

In order to make this experiment with exactness, the 
gases must be quite pure. The oxygen, when obtained by 
means of chlorate of potash, is of sufficient purity ; but the 
hydrogen, when evolved by means of zinc and acid, con- 



696 



MISCELLANEOUS FACTS 




tains impurities, probably sulphurous acid gas, and must 
therefore be passed through a solution of potash, in order 
to make it fit for the experiment. 

For this purpose, the simple apparatus Fig. 69, may be 
employed. Or a similar one may be readily constructed by 
means of two wide mouthed vials, bent glass tubes, and 
corks. We shall however leave this to the ingenuity of the 
experimenter. 

Fig* 69, This apparatus consists 

of the larger bottle, httv- 
ing the cork pierced with 
two apertures for the ad- 
mission of the two tubesy 
of which a is for the intro- 
duction of the sulphuric 
acid, and e, /, for the es- 
cape of the gas. The 
granulated zinc being first 
^placed in the bottle, the 
acid is poured in hy the 
widened tube at &, when the gass thus produced, rises and 
passes the tube /, into the second bottle, to the bottom of 
which the tube dips, through a solution of potash. The 
gas thus rising through this solution, passes through the 
tube leading to the gasometer, in a purified state. The 
hydrogen thus purified is ready for use by means of the 
apparatus next to be described. This consists of a glass 
Fiff. 70. cistern e, Fig. 70, for holding the mer- 
cury ; a graduated tube, a, for the gases ; 
a support to keep this tube from fall- 
|ing ; and a charged Leyden jar, coated 
Binside and out, together with a chain as 
a conductor. The tube is graduated by 
means of a small vessel, Avhich is to be 
filled with mercury, and poured into it. 
The quantity is to be definite, say a 
square inch, being the capacity of the 
cup, so that we know by the number of 
times the cup full is poured in, how 
many square inches of bulk the tube 
contains. The tube being thus filled, 
is inverted in the mercury, as repre- 
sented in the figure. Then allowing 
the oxvffcn to enter at the lower end of 




AND EXPERIMENTS. 397 

the tube, its quantity is exactly ascertained by the fall of the 
mercury as indicated by the markings on the tube, each 
mark being equal to a square inch, or a cup full of the mer- 
cury. Having admitted the oxygen, the hydrogen must be 
allowed to enter in small quantities at a time, to prevent ex- 
plosion. The manner of ignition by this apparatus is quite 
simple. The tubes being pierced near the top, pieces of 
platina or iron wire are inserted, their points coming within 
striking distance inside the tube. Then having charged the 
vial, hold the chain in contact with the foil on the outside, the 
other end of the same being fastened to one of the wires 
which enter the tube, as seen at h. Now touch the other 
wire c with the brass nob, connected with the inside of the 
charged jar, and it is plain that the electric fluid, in passing 
from the positive to the negative side of the jar, must pass 
from the point of one of the wires to that of the other, within 
the tube, and thus the hydrogen is inflamed, its combustion 
being supported by the oxygen. 

As the gases are consumed, the mercury will rise in the 
tube, showing exactly what number of cubic inches disap- 
pear, and also what quantity of water they form. 

If more than twice the quantity of hydrogen, than there is 
of the oxygen, is admitted, it will remain in the tube uncon- 
sumed, and so on the contrary, if the oxygen is more than 
half the bulk of the hydrogen, it will remain pure oxygen. 

Decomposition of Metallic Oxides hy Hydrogen, 

Many of the metallic oxides when heated slightly in the 
hydrogen gas, give ofl* their oxygen to form water with that 
gas, at the same time, the oxide is decomposed by the loss 
of one of its components. Thus while one compound is 
decomposed, another is forming from one of its elements, 
and by proceeding carefully, we are enabled to detect the 
exact composition of each. 

35 



398 



MISCEI.LANEOUiN FACTS 

Fio', 71. 




The apparatus Fig. 71, is designed for this purpose. It 
consists of the flask «, in which the hydrogen is slowly 
generated, by first introducing pieces of zinc, and then pour- 
ing through the pipe h, sulphuric acid much diluted. In 
general a little water in the form of vapor rises with the hy- 
drogen, for the collection of which the two bulbs c, c, are 
designed. If the gas still contains vapor, this is entirely 
withdrawn by passing through the tube d, which contains 
dry chloride of lime, a salt having a remarkable attraction 
for water. It therefore passes into the globe c, in a per- 
fectly dry state. 

The ball c contains the metallic oxide to be decomposed, 
that of copper, for instance. After the apparatus is filled 
with hydrogen this ball is heated by means of a spirit lamp, 
until the oxygen begins to be evolved, when uniting with 
the hydrogen, the heat thus produced keeps the copper red 
for a considerable time, thus producing a curious little self- 
acting furnace, the heat expelling the oxygen from the cop- 
per, which in its turn becomes the means of furnishing the 
heat. Before the process begins, the ball e is w^eighed 
empty, and then with its oxide of copper in it, and thus the 
weight of the copper is known. The weight of the globe g 
is also found, as well as that of the chloride of lime in the 
tube h. The water that is formed in e, passes down into g, 
and if any vapor escape from g, it will be absorbed by the 
chloride of potash in the tube h. At the end of the process, 
the weight of the water formed will be found by weighing 
the globe g, with the water in it, and also weighing the 
chloride in /?, and comparing the sum of these weights with 
what they weighed before. The loss of weight in e will 
show how much oxygen was given off" by the oxide of cop- 
per, and thus by estimation the bulk of oxygen can be 



AND EXPERIMENTS. 



399 



known, which the oxide of copper gave out. The quantity 
of hydrogen contained may also be estimated, by that of the 
oxygen, the weight of this being known. Thus the defi- 
nite proportions of the elements of water, and the composi- 
tion of an oxide may be ascertained by the same process. 

Combination of cliloinne and sulphur. 

The combination of chlorine with sulphur, forms a curi- 
ous compound called cliloruret of sulphur. The method of 
forming this combination, is as follows: 

The materials for making chlorine, it will be remembered, 
are black oxide of manganese, and muriatic acid. These 
being placed in the flask a, Fig. 72, and the heatof a lamp 

Fig. 72. 




applied, the chlorine will rise, and pass down the tube into 
the globe 6, where any water it contains is condensed. Ri- 
sing from h, the gas passes through the tube c, containing 
chloride of calcium, by the absorption of which, it will be 
deprived of all moisture, so that it will arrive at e, which 
contains the sulphur, in a perfectly dry state. The globe 
e must be gently heated by means of a spirit lamp, so as to 
melt the sulphur. 

By these means, the sulphur and chlorine are made to 
combine and pass in the gaseous state into the globe^, 
which being kept cold by means of a stream of water from 
the cistern A, the compound is condensed into the liquid 
form. The quantity of water is regulated by means of the 
stop-cock i, affixed to the tube k, and falls from the globe 
into the dish o. The superfluous gas passes off* into the 
open air, by the waste pipe I. By this method small quan- 
tities of the chloruret of sulphur may be formed. 



400 



MISCELLANEOUS FACTS 



Chloruret of sulphur is a yellowish red fluid, of a pecul- 
iar and disagreeable odor, whose boiling point is 346°. It 
sinks in water, by which in a short time it is decomposed, 
and resolved into hydrochloric and sulphuric acids, and sul- 
phur. The chlorine coaibines with the hydrogen of the 
water, while the oxygen of the water combines with one 
fourth part of the sulphur thus set free to form sulphuric 
acid. The remaining three parts of the sulphur are sepa- 
rated in the solid form. 

Chloruret of sulphur is composed of 100 parts of sulphur, 
and 110 parts of chlorine, by weight. 

By allowing chlorine to pass over this compound for a 
time, another portion is absorbed, and a new compound is 
formed, which contains twice as much chlorine as the chlo- 
ruret ; this is a chloride of sulphur, and is of a dull red 
color. 

The chloruret dissolves sulphur, and is capable of taking 
up much more when heated than when cold. Hence if the 
heated solution be saturated, and then cooled, beautiful 
crystals of sulphur are deposited. 

The volume of oxygen is not clianged by being saturated with 

carbon. 

This fact has already been stated when treating of the 
combination of carbon and oxygen, but the following method 
of demonstrating it ought not to be omitted^ as the most 
satisfactory that has been proposed. 

The thin glass globe. Fig 73, is furnished with a tube 6, 
Fig. 73. and stopcock. a is a little basket 

standing on a piece of iron wire. 
Into the little basket, two or three 
small diamonds are placed, the globe 
, being previously filled with pure oxy- 
gen gas. Before setting the dia- 
'monds on fire, the tube b is placed 
in a cistern of mercury, and the stop- 
cock turned, and the height at which 
the mercury stands in it particularly 
noticed. The stop-cock being again 
turned to prevent the escape during the 
combustion, of the oxygen gas, the dia- 
monds are then set on fire by means of 
a burning glass, which concentrates the 
rays of the sun, sending them through 




AND EXPERIMENTS. 401 

the side of the globe to the basket. In tliis manner the 
diamonds are fired, and will continue to burn until quite 
consumed, leaving not a particle of ashes, or other residue 
behind. 

When the process is finished, and the apparatus has cool- 
ed down to the same temperature that it had before the ex- 
periment, the tube is again to be placed in the mercury, 
and the stop-cock turned. Now if the oxygen had gained 
in bulk by its combination with the diamond, then it is plain 
that the elasticity of the contents of the globe would push 
the mercury lower down in the tube than before, while if it 
had lost in bulk it would rise higher than before. But 
neither of these cases happen, for if the experiment be care- 
fully made, the mercury is always found to remain precisely 
at the same point before and after the experiment. It con- 
sequently follows, that the carbonic acid which is formed 
by the combination of oxygen with carbon, occupies exact- 
ly the same space that the pure oxygen did. By weighing 
the oxygen and the diamonds before the burning, and then 
the carbonic acid after, it is found that the latter is just 
equal to both the former. 

By weight, the following are the results: 100 parts of 
carbon combine with 261.34 parts of oxygen to form car- 
bonic acid; and 100 parts of carbonic acid contain 72.325 
oxygen, and 27.675 carbon. 

SULPHURET OF CaRBON. 

This singular compound, as the name indicates, is com- 
posed of sulphur and carbon. These substances unite only 
in one proportion. By merely heating them together, no 
combination takes place, the sulphur burns away, or passes 
off in vapor, and the charcoal remains unchanged ; but by 
bringing the vapor of sulphur into contact v/ith charcoal 
at a red heat, the combination takes place immediately. 
For this purpose a porcelain tube is sometimes employed, 
but one of cast iron, or a gun barrel, coated with clay on 
the inside, is better. For this purpose, the clay is formed 
into a thin paste, with water, and poured into the tube, this 
being at the same time rolled so that the clay will cover 
every part. After one coat is applied, and dried, by heat- 
ing the tube, the same process is repeated, until the sur- 
face is well covered, and the iron is thus protected from 
the action of the sulphur. If the tube is not well prepared, 
35* 



402 



MISCELLANEOUS FACTS 




the experiment will fail entirely, since the action of the sul- 
phur in a few moments would destroy the iron. 

The tube well covered, is filled with burning charcoal, 
and laid in the furnace, Fig 74, until it attains a white heat. 
. The end h, of the 

-^^^* tube, is closed with 

a piece of clay, and 
at a there is an aper- 
ture for the admis- 
sion of the sulphur^ 
this is also furnish- 
ed with a stopper of 
clay. A long glass 
tube is attached to the iron pipe at c, and passes into the 
capacious flask, y, through an aperture in the side. In the 
absence of such a flask, a double necked bottle will do. A 
waste pipe m arises from the flask, and leads into the open 
air through a window, so as to avoid the fumes of the sul- 
phur. At the bottom of the flask some water is placed, to 
receive the product of the experiment. The flask and 
glass tube should be kept cold during the whole process. 
For this purpose, the tube should be surrounded by a cloth 
kept wet with water from the cistern c, and the flask sur- 
rounded with ice. 

When the apparatus is ready, and the iron tube is at a 
white heat, the stopper a is to be removed, and pieces of 
sulphur dropped in, and the stopper instantly returned to 
its place. The sulphur instantly melts, and in passing 
through the hot tube, which is a little inclined, is converted 
into vapor, and at the same time unites with the charcoal, to 
form the compound in question. 

The sulphuret of carbon, being condensed by the cold 
tube, flows along into the flask, and sinks in the water it 
contains. 

A more simple method of producing the sulphuret of 
carbon, where it is designed to make it in quantities, is the 
following : 

♦ A cast iron cylinder is procured, having a cover through 
which pass the tubes 6, c, Fig. 75. The cylinder is to be 
coated with clay in the manner above described for the 
iron tube, and then filled with charcoal, the tube 6 being in 
its place as shown by the figure. The cylinder is then to be 
placed in a furnace, and heated to redness, and then the 



AND EXPERIMENTS. 

Fig. 75. 



403 




sulphur introduced through the tube h, the aperture of 
which must be immediately closed. The melted sulphur, 
passing down the tube to the bottom of the cylinder, is there 
converted into vapor, and passing through the ignited 
charcoal combines with it, and rises by the iron tube c, into 
the glass tube e, along which it is condensed. The tube d 
leads from a cistern of water, which is allowed in small 
quantities to run in a trough containing the glass tube, and 
from which it is conducted by the string A, to the dish x, 
Thesulphuret as it is formed, passes down the tube/'into the 
vessel n, this being half filled with pounded ice. The waste 
pipe, m conducts away any superfluous gas which is genera- 
ted during the process. 

Whenever all is prepared as above described, the intro- 
duction of small quantities of sulphur by the tube 6, will in- 
sure the production of the compound in question, so long as 
any charcoal remains in the cylinder. It is apt, however, 
to contain some impurities, and must be distilled with chlo- 
ride of calcium. 

Pure sulphuret of carbon is transparent and colorless, 
and insoluble in water. It has a strong, disagreeable smell, 
peculiar to itself, and is soluble in alcohol, and ether. Its 
specific gravity is 1.272, and it boils at 127°, evaporating 
very rapidly during the process. Its freezing point is 60° 
below zero. In the open air, it is exceedingly volatile, and 
the cold it thus produces is intense. Under the exhausted 
receiver of the air pump, the evaporation of course is still 
more rapid. In this situation, a thermometer bulb, covered 
with fine lint, and moistened with this fluid, carried off" the 
heat so rapidly by evaporation, that the mercury was frozen 
in the tube, and on substituting an alcohol instrument, the 



404 MISCELLANEOUS FACTS 

fluid sunk down to 80° below zero. Sulphuret of carbon is 
soluble in fixed and volatile oils, and and it dissolves cam- 
phor, phosphorus and sulphur. When the two latter sub- 
stances are dissolved in it separately, the evaporation of the 
fluid causes crystals of them, of remarkable regularity and 
beauty, to be deposited. 



Carho- Sulphur I c Acid, 

It appears from the experiments of M. Zeise, Professor of 
Chemistry at Copenhagen, that carbon and sulphur form a 
base which is acidifiable by hydrogen. This he has named 
from the yellow color of its compounds, Xantlwgene ; the 
acid he terms liydroxanthic acid, "When an alcoholic solu- 
tion of carb. potassa is mixed with sulphuret of carbon, a 
compound is obtained, which being evaporated under the 
exhausted receiver of an air pump, over a surface of sul- 
phuric acid, or exposed to a temperature of 32°, deposits 
acicular crystals, v/hich become yellow by exposure to air ; 
are very soluble, from which, upon the addition of dilute 
muriatic or sulphuric acid, an oily-looking fluid, heavier 
than water is separated, which is the hychoxantliic acid. 
Exposed to air it becomes covered with an opaque crust ; it 
reddens litmus ; tastes sour, astringent, and bitter; is in- 
flammable, and at 212° is decomposed into bisulphuret of 
carbon, and a peculiar inflammable gas. The action of 
ammonia on the sulphuret of carbon is very peculiar, and 
several new compounds result; but upon these subjects the 
student must consult some more extended treatise. 

Analysis of the combinations of Carbon, Azote, Hydrogen 
and Oxygen. 

The method by which these analyses are made is most 
important, as by such means only, do we become acquainted 
with other substances, through the combination of which 
we obtain light and heat, but more particularly with the 
composition of important combinations, formed both in the 
vegetable and animal kingdoms. During the combustion of 
wood, oil, or any other substance consisting of carbon, hy- 
drogen, and oxygen, we perceive that there is no residuum, 
or at least, a very inconsiderable one in the form of ashes ; 
we have therefore to inquire what combinations have taken 



AND EXPERIMENTS. 405 

place which have escaped our observations. In burning 
substances under bell glasses, or in close vessels, we find 
that carbonic acid and water are formed, with the composi- 
tion of which we are sufficiently acquainted. We may 
therefore, by the method proposed, calculate accurately how 
much carbonic acid and water are procured from burning 
a substance. We first ascertain how much carbon and hy- 
drogen it contains ; then the quantity of oxygen it contains 
after combustion, is found by weighing it before it is burned, 
so we know that the addition of weight to the carbon and 
hydrogen, is due to the oxygen they absorbed during com- 
bustion. The quantity of oxygen may also be discovered 
in a direct manner by estimating what quantityjs necessary 
for the combustion of any particular substance or substan- 
ces, when they are combined. Thus, one volume of oxy- 
gen gas produces one volume of carbonic acid gas ; if there- 
fore, the bulk of carbonic gas after combustion, is less than 
that of the oxygen employed, we conclude the loss is owing 
to its combination with the hydrogen of the burned body, 
forming water. By calculating the quantity of oxygen in 
the water formed by combustion, we may find how much 
hydrogen the burning substance contains. This is easy, 
since we know^ that the two gases composing water, occupy 
2000 times more bulk than the water itself, and that the pro- 
portions of hydrogen and oxygen forming water, are in bulk, 
as two of the former, to one of the latter. Considerable dif- 
ficulties however are offered to an accurate analysis of all 
the substances formed during complete combustion. 

Chemists formerly endeavored to analyse, by mixing sub- 
stances containing oxygen with combustibles, and to which 
the oxygen would be imparted at high temperatures, and 
then calculate the water and carbonic acid formed during 
the process. Formerly chlorate of potash was employed for 
this purpose, instead of which oxide of copper is now used. 
In employing chlorate of potash, oxygen is disengaged from 
the salt, at the same time that carbonic acid and water are 
forming, the heat being sufficient to decompose that salt, 
whereas the oxide of copper has not this defect, as it fur- 
nishes oxygen only as it is employed in the production of 
carbonic acid and water, the hydrogen and carbon used for 
these purposes, being furnished by the combustible substance 
under analysis. Should any vegetable used in analysis, fur- 



40G MISCELLANEOUS FACTS 

nish nitrogen, it will not enter into any combination, but 
will separate as gas, and in this state may be collected and 
estimated. 

The oxide of copper employed for this purpose is best pre- 
pared by dissolving some copper in nitric acid, then evapo- 
rating the solution in a porcelain dish, and afterwards rais- 
ing the teaiperature so high as to drive off the water of crys- 
tallization. It is finished by heating for half an hour, or 
longer in a crucible, taking care not to fuse the oxide which 
remains. The same oxide may be employed for several 
experiments, by merely pouring a little acid on it, by 
which oxygen is absorbed, after which it must be calcined 
as before. 

Ultimate Principles of Vegetables ; few in number. 

Before proceeding to point out the method of detecting 
the elements of vegetables, we must state more definitely 
what they contain. Besides the elements named at the head 
of this section, and which compose the chief parts of the 
whole vegetable kingdom, namely carbon and water, the 
hydrogen and oxygen being merged in the latter, and the 
azote being in small quantity, or often entirely wanting, 
there are still several others which are often found in vege- 
tables, though but in small quantities. In their juices there 
exist minute portions of lime, soda, or magnesia; these are 
combined with the acids of the plant, and are obtained by 
burning, being left with the ashes. Some plants, as the 
equisetum or scouring-rush contains silica ; sulphate of lime 
is found in clover; nitrate of potash in the sap of the sun- 
flower, and nitrate of soda in barley. Common salt, and 
some other chlorides, are frequent ingredients in marine 
plants ; phosphate of lime is found in oats, and some other 
plants, and nearly all vegetables yield traces of oxide of iron, 
and many, oxide of manganese. 

In the process to be described, it is not proposed to enter 
into the subject so minutely as to enable the student to de- 
tect these adventitious substances, but only to show how 
the principal elements are detected during destructive dis- 
tillation. 

We know that the chief elements of vegetables are car~ 
bon, hydrogen, and oxygen, but that we may take the sin> 



AKD EXPERIMENTS. 407 

plest case to illustrate the means of detecting these elements, 
we will suppose the subject of analysis consists only o{ car- 
bon and hydrogen. In this case it is obvious that their entire 
combustion in oxygen gas, would afford nothing but car- 
bonic acid and water. Now let us see how we shall come 
at the proportions of these. The quantity of carbonic acid 
being determined, either by weight or measure, the propor- 
tion of carbon could be inferred ; and this ascertained and 
compared with the original weight of the substance to be 
analysed, would give the proportion of hydrogen. Thus, 
suppose that 7 grains of the substance under analysis, 
yielded by combustion in oxygen, 22 grains of carbonic acid, 
then we should know that the quantity of carbon present 
was 6 grains, or 1 proportion of carbon united to two pro- 
portions of oxygen, 16 grains -22 grains of carbonic acid. 
The 1 grain of hydrogen of course combined with oxygen, 
to form w^ater, and as these unite in the proportions of 1 and 
8, there would result 9 grains of water. 

Suppose in another instance, the weight of the compound 
to be analysed was 15 grains, and that it was composed of 
hydrogen, oxygen, and carbon, as a piece of wood ; and that 
on subjecting it to heat with oxide of copper, we obtained 
22 grains of carbonic acid, and 9 grains of water, then the 
result would be by inference, that the wood contained car- 
bon 6, hydrogen 1, and oxygen 8=15, because, there being 
9 grains of water, we infer by the law of definite proportions, 
hydrogen 1, oxygen 8=9, and there being 22 grains of car- 
bonic acid, this by the same law, is composed of carbon G, 
and oxygen 16=22. Now since there was only 15 grains 
of the wood, we infer that 1 proportion of the oxygen was de- 
rived from the wood, and 1 proportion from the oxide of 
copper. 

The substance to be analysed must first be reduced to 
powder, if capable, if not into small pieces, and mixed with 
about 100 times its weight of oxide of copper, then the mix- 
ture is to be dried in the vacuum of an air pump, wherein 
is also a small vessel of sulphuric acid. The substance for 
analysis is first heated to about 212"", or higher if it will bear 
it, and in this state set under the receiver, before containing 
the acid, and then the air exhausted. The acid by its affi- 
nity to water, abstracts all the moisture still retained by the 
substances in the dish. 




408 MISCELLANEOUS FACTS 

The mixture to be analysed being thus prepared, it is 
Fig\ 76. introduced into the 

tube of green glass a, 
Fig. 76, which is 
open at the large end, 
^and drawn out into a 
finepoint attheother, 
"to which is attached 
the small glass globe c, communicating with the pipe d^ 
which contains chloride of calcium. From the tube d, there 
passes a crooked tube leading under the bell-glassy, which 
stands in the mercury bath g. The orifice of the tube a, 
being closed by a piece of clay or otherwise, the tube is 
heated very gradually by burning charcoal, the screen 5, ac- 
cording to the directions of Prof. Mitscherlich, being neces- 
sary ^* for the purpose of preventing the heat from spreading 
too rapidly, lest the glass should become fused.'' 

By means of the heat, the carbon and hydrogen of the 
substance to be analysed, unite with the oxygen given out 
by the oxide of copper, so that a complete combustion goes 
on within the tube, and water and carbonic acid are com- 
posed. The water collects in the globe c, and if any va- 
por passes, it is absorbed by the chloride of potash in 
the tube d. That part of the apparatus being carefully 
weighed both before and after the process, the excess of 
weight must be due to the water. The carbonic acid passes 
along and escapes into the bell-glass/", within which is the 
small glass globe e, filled with moist caustic potash, into 
which the carbonic acid is directed, where it is instantly ab- 
sorbed by the potash, and thus the additional weight of the 
globe and its contents, will indicate the amount of carbonic 
acid generated during the process. Both the water and acid 
formed during the analysis, can be determined in the manner 
already pointed out, through the aid of definite proportion. 
If any nitrogen is evolved during the process, this will be 
retained under the bell-glass, and its quantity estimated. It 
will not be absorbed by the potash which takes up the car- 
bonic acid. Or perhaps where the elements are compli- 
cated, one experiment had better be made for the nitro- 
gen alone. 

Tannin. 
The importance of the tannin principle which is possessed 
by a great number of vegetables, in an economical relation, 



AND EXPERIMENTS. 409 

has induced the author to add something on that subject in 
this place. 

Tannin is especially distinguished from all other sub- 
stances by its forming an insoluble precipitate with glue, 
isinglass, or any other animal jelly, and hence its use in the 
process called tanning, or making leather, which thus be- 
comes in a degree impermeable to water. 

The relative proportion of tannin in different vegetables, 
is nearly indicated by the weight of the precipitate, which 
they afford in a strong solution of isinglass. The follow- 
ing table by Cadet, shows the relative proportions by the 
weights of their precipitates formed with that substance, 
in infusions of 100 parts of the respective vegetables 
named. 

Galls, - - - - 80 

Tormentil root, - - - - 50 

Alder bark, - ... 36 

Apricot bark, - - - - 32 

Pomgranate rind, - - - 32 

Oak bark, - - - - 25 

Cherry bark, - - - - 24 

Cornus, (dog wood) bark, - - 19 

Sycamore tree bark, - - - 16 

Weeping willow bark, - -= - 16 

Bohemia olive bark, - - 16 

Coryaria myrtifolia bark, - - - 13 

Pinus typhinum bark, - - 10 

Green acorn cups, - - - - 10 

Service tree bark, - - ^ 8 

Horse chestnut bark, - - - 6 

American Sumac bark, - - 6 

No observations are necessary on this table ; the numbers 
show for themselves, the great difference in vegetables 
with respect to the quantity of this matter they contain. 

The next table is by Sir Humphrey Davy. In this, the 
first column shows the whole quantity of extractive obtained 
from 100 parts of the different substances, and the second 
column, the proportion of tannin in that extract. 

Extrai t. Tannin, 

Galls, - - - 37.5 26.4 

Inner oak bark, . , - 23.5 16 6 

Inner horse chestnut, - 18.5 15.2 
36 



410 MISCELLANEOUS FACTS 





Extract. 


Tannin, 


Entire oak bark, 


- 12.7 


6.3 


Entire horse chestnut, 


11.0 


4.3 


Entire elm bark, 


- 


2.7 


Entire willow bark, 


- 


2.2 


Sumac, 


- 34.3 


16.2 


Souchong tea, 


32.5 


10.0 


Green tea, 


- 


8.5 


Calechu, (Bombay,) 


- 


54.3 


Calechu, (Bengal,) 


- 


48.1 



The extractive is obtained by boiling the vegetable mat- 
ter in water, and afterwards evaporating the fluid. Ob- 
tained in this manner it is however, impure, containing not 
only the coloring matter of the plant, but also resin, and 
oil. When purified, extractive is a peculiar vegetable prin- 
ciple, which is the same, from whatever plant it is obtained. 

The following table from Davy's Agricultural Chemistry, 
shows, the average quantity of tannin contained in 480 
pounds of different barks. The entire bark means the bark 
as it comes from the tree, not shaving off the poorest parts, 
as is sometimes done, before it is used. It appears that the 
inner layers of the oak contains much the largest propor- 
tion of tannin. 

Ihs. 

Entire bark, oak cut in the spring, - 29 

'' Spanish chestnut, - - 21 

'' Willow, - ' - - - 33 

^' Elm, - - - - 13 

*' Common willow, - - - 11 

'' Ash, - - . . 16 

'' Beech, - - - - 10 

" Horse chestnut, - - 9 

" Lombardy poplar, - - - 15 

" birch bark cut in the spring, - 8 

'* Hazel, - - - - 14 

" Black thorn, ... 16 

'* Coppice oak, - - - 32 

" Oak cut in autumn, - - 21 

'* Larch in autumn, - - - 8 

*' Oak, corical layers, - - 72 



and experiments. 411 

Pure Tannin. 

Several processes have been suggested for the separation 
of pure tannin from the solutions in which it is combined 
with other vegetable principles. These processes consist 
in throwing down the tannates of lead, or tin, by means of 
thesubacetate of lead, or chloride of tin, these being after- 
wards decomposed by sulphuretted hydrogen ; or by throw- 
ing it down in combination with sulphuric acid, which is 
afterwards abstracted by means of carbonate of lead, or 
barytes. By such means, solutions of a more or less pure 
tannin are obtained, which are filtered through animal char- 
coal, and then cautiously evaporated, the heat employed, 
being no greater than that of a water bath. But experi- 
ment has shown, that the salts, or acid, employed in the 
process, changes the nature, or quality, of the product, and 
that tannin thus procured, is unfit for nice experiments. 

The following process is said to be without such objec- 
tion. The lower opening of an elongated glass vessel, is 
loosely closed by a piece of linen, or a plug of tow, and it 
is then half filled with powdered galls, gently pressed down. 
Common ether is then poured in, and the upper orifice 
being closed so as to admit a little air, but prevent evapora- 
tion, it slowly filters through the galls into a vessel under- 
neath, where it forms two distinct liquids, one on the other ; 
the upper, light and very fluid, the other more dense and 
slightly yellow ; more ether is poured in from above, until 
the lower stratum is no longer increased in quantity, or the 
tannin is all dissolved. The liquids are then poured into a 
funnel, the tube of which is at first stopped by the finger, 
and when they have separated into two portions, the heaviest 
is drawn off into a capsule, and the lighter put aside for 
distillation, it being chiefly ether. The denser liquid is 
then washed with ether, from which it is separated as before, 
and then evaporated in a stove, or what is better, under the 
receiver of an air-pump. A spongy mass is thus obtained, 
of a yellow^ish tint, and amounting to 35 or 40 per cent, of 
the galls employed. This is tannin, as pure as it can be 
procured. 

Tannic acid. 

When prepared as above direjcted, tannin has acid prop- 
erties, and hence is termed tannic acid. It is eminently 



412 MISCELLANEOUS FACTS 

astringent to the taste, without bitterness, is sparingly sohi- 
ble in water, and reddens litmus. It decomposes the alka- 
line carbonates, as those of potash, and soda, with efferves- 
cence, and forms insoluble precipitates with metallic solu- 
tions, thus forming salts, which are true tcmnates. The 
aqueous solution of tannin may be preserved for a long 
time without change, provided the air be entirely excluded, 
but in the open air it absorbs oxygen, evolves carbonic 
acid, becomes turbid, and is converted into gallic acid. 

Ink, 

The class of salts, formed by the tannic acid, with me- 
tallic bases, are generally of no use; there is one of this 
number, however, which is important, and deserves to be 
noticed. This is i\\Q pert aim ate of iron, which forms the 
basis of common ivriting ink. 

The chief ingredients in making ink, are galls, and sul- 
phate of iron, and the most important part of the process, 
is to regulate these ingredients in due proportion to each 
other. If the sulphate be in excess, though the ink may at 
first be of a good color, it will ultimately become brown, 
or yellow. Hence ink-makers should try their fluid from 
time to time, in order to detect this defect, and regulate 
the compound accordingly. Gum is added to ink to retain 
the coloring matter in suspension, to prevent too great flu- 
idity, and to protect the vegetable matter of the galls, from 
decomposition. Logwood, and other vegetable astringents 
have been tried as a substitute for galls, but are found not 
to answer. 

The following is said to form as good a compound for 
ink, as has been tried. Something, however, will depend 
on the paper, for if it is made of inferior rags, and bleach- 
ed with an excess of chlorine, the ink, however good, will 
fade. 

Aleppo galls, broken. 6 oz., sulphate of iron 4 oz, gum 
arabic 4 oz., water 6 pints. Boil the galls in the water, for 
an hour, and then add the other ingredients, and preserve 
in a wooden, or glass vessel. In about two months, strain, 
and put the ink into well corked glass bottles. To prevent 
mould, add one grain of corrosive sublimate dissolved in 
water, to each pint. 

The blue ink, or writing Jliiicl, is said to be composed of 



AND EXPERIMENTS. 413 

sulphate of indigo, and tannogallate of iron. It appears to 
have several objections against it, but not a single advan- 
tao^e over the old writings ink. 

Art of Dyeing. 

Under the article coloring matter, we have given a few of 
the principles of the art of dyeing, but the importance of 
the subject in connection with the arts of life, make it 
proper that we should here refer more particularly to those 
processes, in which Chemistry is directly concerned. 

In the first place, the goods to be dyed, are to be thor- 
oughly cleansed from oily, or gummy matter, this is called 
scouring. Goods which have been previously bleached^ that 
is, whitened, by laying them in the sun, and wetting them 
with lye water, or by the process of chlorine bleaching, re- 
quire little, or no preparation for the dye. The ordinary 
course at dying establishments, where the goods are receiv- 
ed directly from the loom, is the follov/ing. 

The linen, or cotton goods, being first washed in warm 
water, are then howked, as it is termed, that is, boiled in a 
weak solution of caustic potash, then washed in large 
quantities of water, and spread upon the grass, so as to be 
exposed freely to the joint agencies of air, and light, and 
moisture. This operation, which sometimes takes a week, 
or more, may, however, be superseded by the careful ap- 
plication of a weak solution of the chloride of Jime. This 
part of the preparation being finished, the goods are im- 
mersed in water, slightly acidulated with sulphuric acid, 
and again thoroughly washed, and dried. By these opera- 
tions, the texture and durability are without doubt, more or 
less injured, and especially when chloride of lime is used 
unsparingly, in order to hasten the process. 

With respect to the nature of the materials to be dyed, it 
is found that different substances not only possess different 
affinities for the coloring matter, but that this is absorbed by 
them in very different proportions. Wool appears to have 
the strongest attraction for the coloring principle ; silk 
comes next; then cotton, and lastly linen and hemp. 

The simple operation of dyeing, that is, plunging the 
material into the dye-tub, is generally, though not exclu- 
sively performed on animal substances, as wool, and silk, 
while the more refined art of printing in devices and pat- 
terns, is done on cotton, forming as a whole, the buisness of 
36* 



414 MISCELLANEOUS FACTS 

calico printing, an art, which, with simple machinery, pro- 
duces nearly the whole effect of the most labored and re- 
fined drawing in colors. 

We have already stated, (p. 310,) that most colors require 
some intermediate substance, in order to make them com- 
bine with the fibre, whether animal, or vegetable, and that 
where they do not require such a substance, they are called 
substantive colors, but where they do, they are called adjec- 
tive colors. The base so required, is called a mordant. 
The substance to be dyed is first impregnated with the mor- 
dant, and then passed through a solution of the coloring 
matter, which is thus fixed in the fibre, and becomes as it 
were, a part of it. That a considerable portion of the dye 
is permanently retained in the fibre is proved by the experi- 
ments of Dr Ure, who found that 100 parts of the ashes of 
Turkey-red calico, which has an alum mordant, afforded 
]6or 17 parts of alumina, while tlie ashes of white calico 
afforded only a trace of that earth. 

Calico printing. 

This is considered the most refined and tasteful branch 
of the dyer's art. It is a species of topical dyeing, or 
printing in colors. The mordants, the principal of which 
are acetate of alumina, and acetate of iron, are first applied 
to the calico by means of wooden blocks, or copper plates, 
upon which the requisite patterns are engraved. The cloth 
is then passed through the cleansing bath, and afterwards 
exposed on the bleaching ground, or washed. The color 
flies from those parts, which have not received the mordant, 
but is pemanently retained on those which have been 
touched by the blocks. That variety of color which we see 
on calicoes, is produced by employing various mordants, 
and different coloring materials. Another method is to put 
on the mordant and the coloring matter at the same time, 
but in these cases particular management is required in the 
selection of the substances employed, and in the mannerof 
their application. When this method is used, the color is 
Jixedhy a steam heat of 212°. 

White spots, upon a dark ground, as in mourning cali- 
co, are sometimes produced by covering the part intended 
to be kept white, with wax, pipe clay, or some other materi- 
al which prevents the contact of the color. Another 
method is, to apply citric acid, thickened with gum, which 



AND EXPERIMENTS. 415 

being put on the plate, or block, is applied in the same 
manner with the mordant. This will prevent the color 
from being retained. Sometimes the color is discharged in 
spots by the application of chlorine in the form of bleaching 
powder, or chloride of lime, a process well illustrated in 
what are known under the name of Bandana handker- 
chiefs. 

Vegetable Alkaloids. 

We have at p. 318 given some account of the vegetable 
alkalies, or as they are now termed, Alkaloids, since which 
time, several new products of this kind have been discover- 
ed, and many new facts respecting those before known, 
have been determined. We will, therefore, here make 
such additions as to keep our readers advised of the pro- 
gress of Vegetable Chemistry. 

The chemical examination of opium has been remarkably 
productive in interesting and useful results. It has led to 
the discovery of several alkaloids, and of other distinct 
principles, some of which are in high estimation as medi- 
cines. The distinct substances found in opium, are mor- 
phia, narcotina, codeia, narceia, meconia, thehaia, and 
meconic acid. 

Morphia. 

The process for obtaining this, has already been descri- 
bed. There are several salts of morphia, some of which are 
important medicines, as the sulphate and muriate. These 
are prepared by dissolving the pure morphia in the several 
acids, whose names they bear. They are colorless, and 
nearly all may be obtained in the crystalline form. They 
are bitter, and give a precipitate of morphia, when these 
acids are neutralized by alkalies. 

Codeia. 

This alkaloid is obtained from the muriate of morphia. 
On dissolving this salt in water, and precipitating the mor- 
phia with ammonia, codeia remains in the solution, and 
after evaporation and crystallization, it may be separated 
by means of ether. 

Codeia crystallizes in acicular or flat prisms, and is col- 
orless and transparent. It is soluble, in dilute acids, with 



416. MISCELLANEOUS FACTS 

which it forms salts. It is distinguished from morphia, by 
its greater solubility in water, by its insolubility in fixed 
alkalies, and by its not being reddened by nitric acid. Its 
medical virtues nave not been reported. 

Narceia, 

This alkaloid was obtained from the watery solution of 
opium, after the morphia and meconia had been precipita- 
ted, and the remainder dissolved in alcohol, assisted by 
heat. The alcoholic solution, on being evaporated, furnish- 
ed a crystalline mass, which being purified, is narceia. 

It is in white, silky crystals, inodorous, bitter, and solu- 
ble in cold or hot water, also in alcohol, but not in ether. 
The acids combine with it forming salts. 

Meconia. 

This is also obtained by digesting opium in cold water, 
precipitating the other principles which it contains by ap- 
propriate alkalies, dissolving the residue in alcohol, and ^ 
finally in ether, after which, on evaporation, meconia re- 
mains. The quantity of this principle is so minute in opi- 
um, that 15 or 20 pounds must be employed, in order to 
obtain any appreciable quantity. 

This, like the other alkalies we have described, is in fine 
crystals, is white, inodorous, and bitter. It dissolves in 
water, alcohol, and ether, being in the last respect different 
from narceia. 

Thehaia. 

This exists in opium, only in very small quantities. It 
is, like the others, a crystalline substance, and when dis- 
solved in dilute acids, forms salts of a distinct character. 

Narcotica. 

Formerly this was not considered one of the opiate alka- 
loids, nor are its characters as such, very distinct, but its 
composition appears to place it among them. The mode 
of obtaining norcotica has already been described. It ex- 
ists in considerable quantities in all kinds of opium, but is 
said to be most abundant in that called Egyptian. 

Narcotica is deposited from its alcoholic, or etherial so- 
lutions in well defined crystals, which are insoluble in cold, 



AND EXPERIMEx\TS. 417 

and sparingly soluble in hot, water. It is soluble in oils, 
and in acids forming salts. Its effects on the system are 
supposed to be entirely distinct from those of morphia. 

3Ieconic acid. 

The meconic acid is obtained by means of complicated 
chemical processes, which it is not necessary here to detail. 
Like the other substances we have just described, it forms 
a portion of common opium, and from which it is obtained 
in transparent crystals of an acid taste. They are soluble 
in water and alcohol, and when combined with alkalies 
form salts called Meconaies. No use is made of them. 

Caffein. 

That luxury, Coffee, has been the subject of many chemi- 
cal researches. But it does not appear that the tortures it 
has undergone, have led to any method by which its aroma 
can be extracted and procured for use. Caffein, a peculiar 
principle obtained in the form of crystals, comes from the 
raw berry, and does not partake at all of the flavor of burned 
coffee. We shall therefore dismiss this for the more agree- 
able examination of 

Roasted Coffee. 

According to the experiments of Cadet, coffee roasted to 
a pale brown, loses about 12 per cent, of its weight; to a 
chestnut brown, 18 per cent. ; and to a black, nearly 24 per 
cent. So that the ordinary loss of weight in coffee roasting, 
may be estimated from 12 to 14 per cent. 

The composition of roasted coffee, according to Shrader, 
is as follows : 

Extractive matter soluble in water and alcohol, 12.5 
Brown gum, - - - - 10.4 

Extractive, soluble in water but not in alcohol, 5.7 
Oil and resin, - - - - 2.0 

Insoluble, burned, v/oody fibre, - - 69.0 



99.6 

It has not been in the power of Chemistry to detect the 
particular principle on which the flavor of burned coffee de- 
pends. Each of the proximate principles of the raw coffee 
being exposed separately to heat, did not any one of them, 
yield any particular flavor, and the ligneous residue, when 



418 MliiCELLANEOUS FACTS 

roasted, acquired as much the characteristic odor, as when 
the other principles were roasted with it. We must con- 
clude therefore, that the flavor of roasted coffee is the joint 
product of all its constituents, and not of any one peculiar 
principle, as an essential oil, as was once supposed. 

The flavor of coffee as a beverage, depends in the first 
place, on the roasting, and in the second, on the mode of 
making the infusion. With respect to the roasting, if burned 
to charcoal, it is little better than carbon from any other 
vegetable. If kept heated for a long time, though not re- 
duced to carbon, it still loses much of its aroma, on what- 
ever this may depend, and if not done though, its taste is raw 
and unpleasant. It should be of a dark chestnut brow^n, 
and is better when done in a close vessel than in an open 
one. It should not be long kept after roasting, and on no 
account should it be ground before it is wanted for use, un- 
less confined in an air tight vessel. The Arabians, who 
are our masters in this respect, do not roast their coffee 
until the moment it is wanted for use. With respect to 
making the infusion, it is sometimes boiled, and sometimes 
strictly infused by straining the hot water through it. In 
the former case, the liquor is more Tiiglily colored^ but in the 
latter, more higlily flavored. 

Elatin. 

The fruit of the Cacumis elaterium or wild cucumber, fur- 
nishes a very acrid juice, which on standing, deposits a pow- 
erful medicine, known under the name of eleterium. The 
active principle in this depends upon a small quantity of 
elatin, and what may be separated by chemical means. 

Gentianin. 

This is the concentrated bitter principle of the common 
gentian root, Gentiana lutca. It is not necessary to detail 
the complicated process by which it is extracted. Gentia- 
nin is yellow, inodorous, very soluble in ether and alcohol, 
and possesses in a most powerful degree, the aromatic bitter 
taste of the gentian, which taste is much increased by solu- 
tion in an acid. As a medicine, it probably possesses the 
virtues of the gentian in a highly concentrated state. 

Thein. 

Tea contains a peculiar principle which may thus be sepa- 
rated. Twelve parts of tea leaves were infused for 24 hours. 



AND EXPERIMENTS. 419 

in 200 parts of cold water, in which 3 parts of common salt 
were dissolved. The infusion was evaporated to dryness, 
and the residue digested in alcohol ; what the alcohol did 
not take up, was dissolved in water, digested with magnesia 
and filtered. On evaporating the filtered liquor, crystals of 
thein are obtained. 

Experiment has shown that the quantity of soluble matter 
is greater in green than in black tea, though the excess is by 
no means so great as the comparative flavors would seem to 
indicate. 

The following table by Sir Thomas Brande, shows the 
respective quantities of soluble matter in water and in alco- 
hol — the weight of the precipitate by isinglass, and the pro- 
portion of inert, woody fibre, in green and black teas of va- 
rious qualities. It is given, not as throwing any important 
light upon the cause of the different qualities and the effects 
of tea, but as containing the results of actual experiments. 
It will be remarked that when the leaves have been exhausted 
by water repeatedly affused, alcohol is still capable of ex- 
tracting a considerable quantity of soluble matter. The 
alcoholic extract, infused in boiling water, furnishes a liquid 
which smells and tastes strongly of tea, and which, were it 
not for the expense of the solvent and the trouble attending 
its separation, might perhaps be profitably employed. 



One hundred parts of ta 


a. 


Soluble 


Soluble 


Precipitate 


Inert 






in water. 


in alcohol. 


with jelly. 


residue 


Green Hyson, 14s. 


lb 


41 


44 


31 


56 


12s. 


(( 


34 


43 


29 


57 


10s. 


a 


36 


43 


26 


57 


8s. 


(( 


36 


42 


25 


58 


9s. 


(< 


31 


41 


24 


57 


Blk. Souchong, 12s. 


cc 


35 


36 


28 


64 


10s. 


ti 


34 


37 


28 


63 


8s. 


<; 


37 


35 


28 


63 


7s. 


(( 


36 


35 


24 


64 


Qs. 


(( 


35 


31 


23 


65 



From this we may remark that the dearest kind of green 
hyson is most soluble in water and in alcohol, affords the 
largest precipitate, and the smallest quantity of inert resi- 
due. It may also be noticed that the cheapest souchong 
affords the least precipitate, the most inert residue, is the 
least soluble in alcohol, while it has an average solubility in 
water. 



420 MISCELLANEOUS FACTS. 



Suga?\ 



The processes by which sugar is manufactured from the 
sugar cane, have ah'eady been sufliciently detailed, p. 307. 
There are however two other sources from which sugar is 
obtained, not mentioned there. These are from the maple 
tree and the beef. 

Maple Sugar, 

This is tlie product of tlic Acer saccharinum or sugar 
maple, which is a forest tree of hirge size, growing in all the 
northern parts of the United States. The sugar is con- 
tained in the sap of this tree, and is procured by boring 
holes a few inches deep into the side of the tree, two or 
three feet from the ground, and inserting little spouts, by 
which it is directed into troughs or tubs, placed on the 
ground. The trees are tapped in March and April, and one 
of ordinary size will yield from twenty to thirty gallons of 
sap in the season. This is said to contain on the average 
about 5 per cent, of sugar. It is boiled down injarge iron 
kettles placed over temporary fire places in the woods. This 
sugar has a peculiar flavor which makes it every where a 
favorite among children as a sweet-meat, for which purpose 
it is almost exclusively employed. It may however be puri- 
fied so as not to differ from the best loaf sugar in appear- 
ance or taste. 

Beet Sugar, 

This is obtained from the Betula vulgaris, a large variety, 
with the root pale red or nearly white, and sometimes yel, 
low\ These roots having been softened in hot water, are 
then sliced and the juice forced out by pressure, which is 
boiled down to about two thirds of its original bulk, with the 
addition of a little lime which neutralizes any acid it may 
contain, and at the same time purifies the liquor, by bring- 
ing an extractive matter to the surface. It is then strained, 
again evaporated and purified by the usual method. In 
France it is estimated that 100 lbs. of the root yields be- 
tween 4 and 5 pounds of purified sugar, at the average rate 
of between three pence and four pence the pound, besides a 
considerable quantity of syrup. 



EaUIVALENTS. 



Table of Chemical Erjuivalents, Atomic Weights, or Proportional 
Numbers^ Hydrogen being taken as Unity.* 

In preparing the following tabular view of the atomic weights. I have 
chiefly consultf;<l the table publishofl by Dr. Thomps^jn in his f'irst Prin- 
ciples of Chf-rnistry, and by Mr. Phillips in the new series, 10th volume, 
of the Annals of Philosophy. From the full account already given of the 
Laws of Combination, and of the Atomic Theory, it will be superfluous 
to descrilKJ the uses of the table. The only explanation required on this 
ffubject, relates to tlie ingenious contrivance of Dr. Wollaston, callfxl the 
Scale of Chemical Equivalents. This useful instrument is a table of 
atomic weights, comprehending all those substances which are most fre- 
quently employed by chemists in the lalKjratory ; and it only ^lifTers from 
other tabular arrangements of the same kind, in the numbers being attached 
to a sliding rule, which xa divided according to the principle of that of 
Gunter. From the mathematical con.struction of the scale, it not only 
serves the same purpose as other tables of atomic weights, but in many 
instances su[>erscdes the necessity of calculation. Thus, by inspectinp" the 
common table of atomic weights, we learn that 88 parts, or one atom, ot 
the sulphate of {X>tassa, contain 40 parts of sulphuric acid and 48 of potas- 
sa ; but recourse must be had to calculation, when it is wished to deter- 
mine the quantity of acid or alkali in any other quantity of the salt. This 
knowledge, on the contrary, is obtained direr:tly by means of the scale of 
chemical equivalents. For example, on pushing up the slide until 100, 
marked u{>on it, is in a line with the name sulphate of potassa on the fixed 
part of the scale, the numl)ers opposite to the terms sulpliuric acid and po- 
tassa, will give the precise quantity of oach contained in 100 parts of the 
compound. In the original scale of Dr. Wollaston. for a particular account 
of which I may refer to the Philosophical Transactions for 1814, oxygen is 
taken as the standard of comparison ; but hydrogen may be selected for 
that purpose with equal propriety. 



Acid, acetic .... 


. 50 


Acid 


, c. 2w. 


42 


c 1 w.t 


59 




carbonic, (c. 6-7-0. 16) • 


22 


arsenic, (a, 38-f-o. 24) 


. 62 




chloric, (chl. 36-H). 40) - 


76 


arsenious, (a. 3&-}-o. IG) 


M 




chloriodic, (chl. 72-j-iod. 124) 


196 


benzoic .... 


. 120 




chloro-carbonic, (chL 36-|-carb. 




boracic, (b. 8-}-o. 16) • 


24 




oxide 14) .... 


50 



• From Turner's Chemistry. 

t C. mcftfUB crystallized, w. water ; and the numeral before w. ezprefloes the number 0/ 
ttoma of water v/hich the cryrtals contain. O. means oxjgerL 



EQUIVALENTS. 



4cld, chlorocyanic (chl. 63-}-cyan. 26) 
chromic, (chr. 28-|-o. 24) • 
citric .... 
c. 2w. . 

columbic . . . - 
fluoboric, (bor. a. 24-1-fl. a. 10) 
fluoric . . . - 

formic 

fluosilicic, (fl. a. lO-f-sil. 16) 

gallic? 

hydriodic, (iod. 124-f-hyd. 1) 
hydrocyanic, (cyan. 26-{-hyd. 
hyposulphiirous, (s. 16-f-o. 8) 
hyposulphuric, (s. 32-j-o. 40) 
iodic, (iod. 124-H. 40) - 

malic 

manganeseous 7 

manganesici 

molybdous 

molybdic .... 

muriatic, (chl. 36-[-hyd. 1) 

nitric, dry (nit. 14-j-o. 40) - 

nitric, liquid (sp. gr. 1. 5) 2 w, 

nitrous (nit. 14-j-o. 32) 

oxalic .... 

c. 4 w. 

perchloric, (chl. 36-f-o. 56) 
phosphorous, (p. 12-1-0. 8) - 
phosphoric, (p. 12-[-c. 16) 
saccholactic .... 
selenic, (sel. 40-f-o. 16) - 
succinic .... 
sulphuric, dry, (s. 16-[-o. 24) 
liquid, (sp. gr. 1 8438) 1 w. - 
sulphurous, (s. 16-|-o. 16) 
tartaric .... 

c. 1 w. 

titanic 

tungstic, (t. 96-}-o. 24) • 
uric - - - • 

,\kohol, (olef. gas 14-|-aq. vap. 9) 
Alum, anhydrous .... 

c. 25 w. . 
Alumina 

sulphate .... 
Aluminum .... 
Ammonia, (nit. H-j-hyd. 3) 
Antimony 

chloride, (ant. 44-f-chl. 36) 

iodide, (ant. 44-[-iod. 124) - 

oxide, (ant. 44-^-0. 8) 

deutoxide . . . - 

peroxide 

jBulphuret .... 
inenic 

eulphuret, (realger) 



62 
52 

58 
76 
152, 
34 
10 
371 
26 
62 
125 
27 
24 
72 
164 
70 
52 
60 
64 
72 
37 
54 
72' 
46 
36 
72 
92 
20 
28 
104 
56 
50 
40 
49 
32 
66 
75 
48 
120 
72 
23 
262 
487 
18 
58 
10 
17 
44 
80 
168 
52 
56 
60 
60 
38 
54 



56-hchl. 36) 



20H-chl. 36) 



Arsenic, sesquisulphuret,* (orpiment) 
Barium 

chloride, (b. 70-1-chl. 36) 

iodide, (b. 70-1-iod. 124) 

oxide, (baryta) 

peroxide ? - - - 

phosphuret 

sulphuret 
Bismuth - - . . 

chloride, (b. 72-|-chl. 36) 

oxide .... 

iodide, (b. 72-i-iod. 124) 

phosphuret, (b. 72-f-p. 12) 

sulphuret, (b. 72-i-s. 16) 

Boron 

Cadmium 

chloride, (cad, 

oxide . 

iodide 

phosphuret 
I sulphuret 

Calcium 

chloride, (cal, 

iodide 

oxide, (lime) 

phosphuret 

sulphuret 
Carbon - 

bi sulphuret, 

chloride 

perchloride 

oxide - 

phosphuret 
Cerium - 

oxide - 

peroxide • 
Clilorine 

hydrocarburet, (chl. 36-f-olef. 
gas 14) 

oxide, (chl. 36-j-o. 8) 

peroxide 
Chromium 

oxide - 

deutoxide 
Cobalt - 

cldoride, (cob, 

iodide • 

oxide 

peroxide 

phosphuret 

sulphuret 
Columbium 
Copper - 

chloride, (cop 

bichloride, (c, 



(c. 6-(-s. 32) 



264-chl. 36) 



64-|-chl. 36) 
. 64-i-chl. 72) 
iodide, (c. 64-f-iod. 124) 



• 1 proportion of arsenic, and 1 1-2 sulphur. 



EQUIVALENTS. 



Copper, oxide, (c. fr4-f-o. 8) 
preoxide, (c. 64-|-o. IG) 
phosphuret 
sulphuret 
bisulphiiret 

Cyanogen, (carb. l2-f-nit. 14) 

Cyanuret of sulphur, (cy. 26-f-s. 32) 

Ether, (olef. gas. 28-{-wat. vap. 9) 

Fluorine .... 

Glucinum .... 

Glucina .... 

Gold 

chloride, (g. 200-|-chl. 36) 
bicliloride, (g. 200-|-chl. 72) 
iodide, (g. 200-i-iod. 124) 
oxide, (g. 200-I-O. 8) 
peroxide, (g. 200-f-o. 24) 
sulphuret, (g. 200-f-s. 48) 

Hydrogen .... 

arseniuretted, (a. 38-|-h. 1) 
carburetted, (c. G+h. 2) 
bicarburetted, (olefiant gas) (c. 

12-h-h. 2) 
selcniuretted, (s. 40-i-h. 1) 
sulphuretted, (s, 16-j-h. 1) 
bisulphuretted, (s. 32-|-h. 1) 

Hydruret of phosphorus 

Bihydruret of phosphorus 

Iodine ..... 

Iridium 

Iron 

chloride, (i. 2S-f-chl. 36) - 
perchloride, (i. 23-|-chl. 54) 
iodide, (i. 28-}-iod. 124) 
oxide, (i. 28-i-o. 8) - 
peroxide, (i. 2<3-f-o. 12) 
sulphuret, (i. 23+8. 16) 
bisulphuret, (i. 28-}-s. 32) 

Lead 



chloride, (1. 104-i-chL 36) 
oxide, (1. 104-f-o. 8) 
deutoxide, (1. lOl-f-o. 12) 
peroxide, (1. ICH-j-o. 16) - 
phosphuret, (1. KH-hp. 12) 
sulphuret, (1. 104-1-s. 16) 

Lithium .... 

chloride, (1- lO-f-ch. 36) - 
iodide . . . - 
oxide, (lithia) • 
sulphuret 

Magnesium .... 
chloride, (m. 12-]-chl. 36) 
oxide, (magnesia) • 
sulphuret 

Man^janese 

chloride, (m. 28-1-chL 36) 
oxide, (m. 28-1-0. 8) 
d<?»]tox^de, (m. 23-f-o. 1?) 



72 

80 

76 

80 

96 

26 

58 

37 

18 

18 

26 

200 

236 

272 

324 

208 

224 

248 

1 

39 

8 

14 

41 

17 

33 

13 

14 

124 

30 

28 

64 

82 

152 

36 

40 

44 

60 

104 

140 

112 

116 

120 

110 

120 

10 

46 

134 

18 

26 

12 

48 

20 

28 



Manganese, peroxide, (m. 28-f-o. 18) 

sulphuret . . . - 
Mercury 

chloride, (calomel) (m. 200-1- 
chl. 36) ... 

bichloride, (corros. subl.) (m. 
200-1-chl. 72) 

iodide, (m. 200-}-iod. 124) 

biniodide, (m. 200-]-iod. 248) 

oxide, (m. 200-i-o. 8) - 

peroxide, (m. 200-^-0. 16) 

sulphuret 

bisulphuret 
Molybdenum 

oxide, (m. 48-1-0. 8) 

deutoxide, (m. 48-1-0. 16) 
Molybdic acid, (m. 48-h). 24) • 
Niclvel, (Lassaigne) 

chloride, (n. 40-1-chI. 36) 

iodide - . - • 

oxide, (n. 40-1-0. 8) 

peroxide, (n. 40-j-o. 16) 

phosphuret 

sulphuret 
Nitrogen 

bicarburet, (cyanogen) . 

ciiloride, (n. 14-|-cli]. 144) 

iodide, (n. M-f-iod. 372) 

oxide, (n. H-j-o. 8) 

deutoxide, (n. 14-i-o. 16) 

Oxygen 

Palladium .... 

oxide .... 
Phosphorus .... 

chloride, (p. 12-[-chl. 36) 

bichloride 

carburet . . - • 

sulphuret 
Platinum 

chloride, (p. 96-t-chl. 36) 

bichloride 
Platinum, oxide - 

deutoxide 

sulphuret 

bisulphuret 
Potassium . . . - 

chloride, (p. 4(H-chL 36) 

iodide 

oxide, (potassa) 

peroxide, (p. 40-|-o. 

phosphuret 

sulphuret 
Rhodium - 

oxide • 

peroxide • 
Selenium 
Silica 
SiUicium 



24) 



44 

44 

200 

236 



EQUIVALENTS. 



Sliver 

chloride, (a UO-hchl. 36) 

iodide 

oxide, (s. 110-i-o. 8) 

pho&phuret 

Bulphuret 
Sodium . . . - 

cliloride, (s, 24-i-chL 36) 

iodide 

oxide, (soda) 

peroxide, (s. 24-i-o. 12) 

phosphuret 

sulphuret 
Strontium - 

chloride 

iodide 

oxide, (sti'ontia) 

phosphui'et 

sulphuret 
Sulphur . . . • 

chloride, (s. IGH-cld. 36) 

iovlide, (s. 16-|-iod. 124) 

phosphuret - 
Sulphuretted hydi-ogen 
Bisulphuretted hydrogen 
Tellurium, (Berzelius) 

chloride 

oxide 
Tin .... 

chloride, (t. BS-f-chL 36) 

bichloride 

oxide 

deutoxide 

phosphuret 

sulphuret 

bisulphuret 
Titanium 
Titanium, oxide 
Titanic acid • 
Tungsten . 

oxide, (brown,) (t. 96-f-o. 
Tungstic acid, (t. 96-f-o. 24) 
Uranium .... 

oxide, . 

peroxide . 
Water • 
fttrium • 
Oxide, (Yttrla) 
Zinc - 

chloride 

oxide 

X^liosphuret 

sulphuret 
Zirconium 
Zirconia - 

SALTa 
Acetate of alumina, (ac a. SO-f-al. 16) 

c 1 w • • • • 



16) 



110 

146 

234 

118 

122 

126 

24 

60 

148 

32 

36 

36 

40 

44 

80 

140 

56 

52 

66 

10 

56 

142 

28 

17 

33 

32 

68 

40 

58 

94 

130 

66 

74 

70 

74 

90 

32 

40 

43 

96 

112 

120 

208 

216 

224 

9 

34 

42 

31 

70 

42 

46 

50 

40 



Acetate of ammonia, (ac. a, 50-|-am. 17) 67 



c. 7. w. 

baryta, (ac. a. 50-t-b. 78) 

c. 3 w. 

cadmium, (c. 2 w.) - 

copper, (ac. a. 50-i-perox. 80) 

c. 6 w. (com. verdigris,) - 

binacetate . - - - 

c. 3 w. (distilled verdigris,) 

subacetate, (ac. a. 50-t-perox. 

160.) 

lead 

c. 3 w. • 

lime ..... 
magnesia . . . . 
mercury, (protoxide) c. 4 w. 



silver • 
strontia, c. 1 w. 
zinc 
c. 7 w. 
Arseniate of lead . 
lime 
magnesia 



13C 
129 
155 
132 
130 
184 
180 
20: 

.21(1 
162 
189 

78 

70 
294 

98 
168 
111 

92 
155 
174 

90 

82 
110 
181 

94 
201 
114 
180 

82 
102 

86 
172 



Binarseniate of potassa, c 1 w. 

Arseniate of soda ... 

Binarseniate of soda, c. 5 W. • 

Arseniate of strontia • 

silver . . . • 

Arsenite of lime 

potassa ... 

Arsenite of soda 

silver - • . • 

Carbonate of anmionia, (carb. a. 22-|- 

am. 17) • . - - 39 

Sesquicarbonate of ammonia, (carb. a. 

33+am. 17-hw. 9) - - 59 

Bicai-bonate of ammonia, 1 w. • • 7C 

Carbonate of baryta - - • 100 

copper lOS 

iron, (protoxide) - . • 58 

lead 134 

lime 50 

magnesia .... 42 

manganese .... 68 

potassa 70 

Bicarbonate of potaasa ... 00 

c. 1 w. • . 101 

Carbonate of soda, ... 64 

clOw. . . . . 144 

Bicarbonate of soda, c. 1 w • • 85 

Carbonate of strontia - - • 74 

zinc 64 

Chlorate of baryta, (ch. a. 76-f-b. 78) 154 

lead 183 

mercury 284 

potassa - • • 124 



EQUIVALENTS. 



Chromale of baryta - 

lead .... 

rr-^rcury . . . - 

potassa, (chr. a. 52-}-?. 48) 
Bichromate of potassa 
Fluate of baryta 

lead 

lime .... 
Muriate of ammonia, (mur. a. 37-j- 
am. 17) ... 

baryta, c. 1 w. 

lime, c. 6 w. • 

maganesia • 

strontia, c. 8 w. 
Nitrate of ammonia, (nit. a. 54-{- 
am. 17) ... 

baryta - - • 

bismuth, c. 3 vv. 

lead - . - • 

lime .... 
Nitrate of magnesia 

mercury, (protoxide) c. 2 w. 

potassa ... 

silver . . . • 

Boda - - - - 

strontia .... 
Oxalate of ammonia, (Ox. a. 36-}- 
am. 17) ... 

c. 2 w. 

baryta .... 
Binoxalate of baryta 
Oxalate of cobalt ... 

lime .... 

nickel . . - , 

potassa ... 

c. 12 w. . 
Binoxalate of potassa 

c. 2 w. • 
Quadroxalate of potassa 

c 7 w. 
Oxalate vf strontia • 



130 
164 
260 
100 
152 

83 
122 

38 

54 
124 
119 

67 
161 

71 
132 
161 

166 
82 
74 
280 
102 
172 
86 
106 

53 
71 
114 
150 
70 
64 
84 
84 
93 
120 
138 
192 
255 



Binoxalate of stronila - • • 134 

Phospliate of ammonia, c 2 w. • 63 

baryta 106 

lead 140 

lime ..... BC 

magnesia ... - 48 

soda 60 

c. 12 w. .... 168 

Sulphate of alumina .... 58 

ammonia, c 1 w. • ► 66 

baryta 118 

Sulphate of copper, (sulph. a. AO-j" 

perox. 80) .... 120 

Bisulphate of copper • • • 160 

c. 10 w. (blue vitriol) • . 250 

Sulphate of iron, (protoxide) - . 76 

c. 7 w. (green vitriol) . . 139 

lead 152 

lime 68 

c 2 w. 86 

lithia, c. 1 w 67 

magnesia, c. 7 w. • • 123 
mercury, (sulph. a. 40-f~pcrox. 

216) .... 160 

Bisulphate of mercury, (peroxide) • 296 

Sulphate of potassa ... 88 

Bisulphate of potassa, c. 2 w. • . 146 

Sulphate of soda .... 72 

c. 10 w. .62 

strontia • - -92 

zinc • • • • 82 

c. 7 w. - . • . 145 

alumina and potassa • • 262 

c, 25 w. (alum) . . • 487 

Nitrate of lead .... 178 

lime 94 

pnrn^"='n . • • • • SS 

Bitartraie oi .tntaspa ... .80 

c. 2 w. (cicain of tartar) • • *>9^ 
Tartrate of antimony and potassa, 

c 3 w. (tartar emetic) • 3f0 



Acetates 

Acetate of copper 
of lead 

Acid, acetic 

antimonious - 
arsenic 
boracic - 
carbonic - 
chloric - 
chromic - 
citric - 
fluoric 

hydrocyanic - 
iodic 
meconic 
molybdic - 
muriatic 
nitric 
nitrous - 
nitro-muriatic - 
oxalic - 
oxymuriatic 
phosphoric - 
phosphorous 
prussic - 
pyroligneous 
sulphurous - 
sulphuric - 
tartaric 
tungstic 
vegetable - 

Agents, imponderable 

Air. atmospheric 
thermometer - 

Affinity, - 

chemical • 
double elective 
elective 
simple - 

Albumen 

Alcohol - - . 

Alembic 

Alkah, volatile - 

vegetable - 

Allanite - - - 

Alloys 



INDEX. 


- 273 , 




300 


Alum . - - . 




301 


Alumina - - - - 


237 


- 


300 


Amalgams - - - 


- 204 




299 


Ammonia - - - - 


146 


- 


255 


liquid 


- 147 




250 


muriate of - 


286 


. 


163 


Analysis of vegetables - 


- 299 




149 


of minerals 


335 


- 


167 


of waters 


- 341 




252 


Animal chemistry 


821 


- 


304 


oils - - - 


- 323 




173 


heat - - - 


328 


- 


191 


Antimony - - - 


- 254 




170 


oxides of - 


255 


- 


319 


sulphuret of - 


- 255 




253 


tartrate of - 


302 


. 


166 


Aqua fortis - - - 


. 144 




144 


regia - - - 


211 


- 


143 


Aqueous fusion 


- 267 




126 


Arrow root 


308 


_ 


301 


Arsenic _ - - 


- 249 




163 


oxide of - 


250 


- 


161 


sulphurets of 


- 251 




162 


test of - 


250 


. 


191 


white - - - 


- 250 




300 


Arsenites - - 


251 


- 


155 


Atmospheric air - 


- 135 




157 


composition of 


135 


- 


302 


Atomic theory 


- 98 


- 


254 


Attraction - . - 


69 




299 


of cohesion 


- 70 


. 


10 


chemical 


70 




135 


Azote - - - - 


- 238 


- 


36 








71 


Balance, portable - 


- 107 


. 


70 


Balloons - - - - 


124 




73 


Barium - - - 


- 225 


- 


73 


protoxide of - 


225 




72 


Barytes - - - 


- 225 


- 


322 


Barley, malting of - 


313 




315 


Barometer - - - 


- 105 


. 


101 


thcrmometric 


18 




147 


Bell glass - - - 


- 106 


. 


318 


Bismuth - - - - 


259 




256 


oxide of - 


^ 259 


- 


202 


flowers of - - 


259 





INDEX. 




Bismuth, magistery of - 


- 259 


Chlorates - - - 


279 


Black lead 


245 


Chlorate of potash 


- 280 


Black oxide of manganese 


- 241 


Chlorides - - - - 


279 


Bleaching powder 


229 


Chloride of nitrogen 


- 168 


Blende - - - - 


- 246 


of calcium 


- 231 


Blood ... - 


323 


of Hme 


229 


Blowpipe, common 


- 102 


Chlorine _ - - 


- 163 


Gahn's 


103 


oxides of - - 


167 


compound 


- 129 


Chlorine and oxygen 


- 167 


Blue, Prussian - 


191 


Chromium - - - 


251 


Bodies, elementary 


- 112 


Chromate of lead - 


. 252 


ponderable 


112 


of iron 


252 


Boiling of liquids - 


17,24 


Chrome yellow 


- 252 


Borates - - - - 


282 


Cinchonia - - - 


320 


Borax - - - - 


- 283 


Cinnabar - - - 


- 204 


Boron - - - - 


163 


Coal gas - - - - 


304 


Brass - - - - 


- 246 


Cobalt - - - - 


- 257 


Bromine - - - - 


172 


oxides of - 


256 






arsenical 


- 257 


Cadmium - - - - 


247 


Cohesive attraction - 


70 


Calamine - - - 


- 246 


Cold, artificial 


- 39 


Calcium - - - - 


227 


Colouring matter 


309 


oxide of - 


- 228 


of the blood - 


- 324 


Calomel - - - - 


206 


art of - 


309 


Caloric - . - 


. 11 


Colours, primary - 


- 45 


conductors of - 


22 


Columbium - - - 


254 


combined - 


- 13 


Combination - - - 


- 79 


free - - - 


13 


by volume 


91 


equilibrium of 


- 12 


Common salt 


- 223 


expansion of - 


25 


Combining proportions 


86 


radiation 


- 29 


Combined caloric - 


- 13 


specific - - - 


32 


Combustion - - . 


118 


sources of - 


- 41 


in oxygen - 


- 119 


of fluidity 


13 


spontaneous 


311 


capacity for 


- 32 


Conductors of caloric 


- 22 


Canton's phosphorus - 


46 


Concave mirrors 


29 


Caoutchouc 


- 319 


Copper - - - 


- 260 


Carbon - - - - 


147 


protoxide of - 


261 


sulphuret of 


- 195 


peroxide of - 


- 262 


Carbon and oxygen - 


149 


sulphuret of - 


262 


Carbonic acid 


- 149 


Copperas - - - 


- 274 


oxide - - - 


154 


Corrosive sublimate - 


207 


Carbonates - - - 


- 284 


Cream of tartar - 


- 302 


Carbonate of potash - 


285 


Cryophorous - - - 


20 


of soda - 


- 285 


Crucible - - - 


- 100 


of lead - 


- 263 


Crystallization - - - 


267 


Carburetted hydrogen 


175 


water of - 


" 267 


Caustic, lunar 


- 278 


Cups, galvanic - - - 


60 


Cerium - - - - 


256 


Cyanogen - - - 


- 191 


Cistern, pneumatic 


. 131 


Cyanuret of mercury 


190 


Chemical affinity 


70 






force of - 


- 83 


Decomposition, double 


76 


combinations 


79 


Definite proportions 


. 86 


apparatus 


- 100 


Decrepitatin - - - 


267 


equivalents - 


93 


Double salts - - - 


- 269 


Chemistry, definition of - 


9 


Destructive distillation 


304 





INDEX. 




Diamond - - - 


- 147 


Galena - - . 


2G2 


Differential thermometer - 


36 


Galvanic battei;y - - - 


61 


Dropping tube 


- 103 


circle - - - 


56 


Diana's silver tree 


208 


trough - - ^ 


59 


Dolomite - - - 


- 46 


poles - - - 


58 






cups - - - 


65 


Earths 


- 236 


pile - - - 


57 


Efflorescence - - - 


268 


Galvanism - - - - 


54 


Elasticity, affects affinity 


- 78 


chemical effects of 


61 


Elective affinity - - - 


73 


heating effects of - 


68 


double 


- 74 


theory of - 


55 


Electricity _ - - 


48 


discovery of - 


48 


conductors of - 


- 52 


Gases, combine by volume - 


91 


theory of - 


51 


expand equally - 


27 


Electrics _ _ _ 


- 49 


their weight - 


109 


Electro-chemical theory 


66 


Gas, oxygen - - - - 


115 


Elements - - - 


9, 112 


hydrogen - - - 


122 


their number 


113 


carbonic acid - - - 


149 


Emetic tartar 


- 303 


carbonic oxide 


154 


Epsom salt _ - - 


272 


chlorine - - - - 


163 


Equivalents - - - 


- 93 


muriatic acid 


166 


scale of, - 


96 


fluoric acid - - _ 


173 


Essential oils 


- 312 


lights - - - 


183 


Ether - - - - 


316 


oleiiant - - - - 


183 


evaporation of 


- 21 


nitrogen - - - 


134 


Etching on glass 


174 


nitrous oxide - - - 


138 


Eudiometry - - - 


- 142 


Gas apparatus - - - 


104 


Extractive matter 


309 


Gelatine _ _ - - 


322 


Expansion by heat 


. 25 


Germination - - - 


290 


of solids 


25 


Gilding - - - - 


311 


of liquids 


- 27 


Glass . - . - 


240 


of gases 


28 


Glauber's salt - - - 


270 


Evaporation 


- 18 


Glucina - - - - 


238 


Evaporating dish 


102 


Gold 


210 






etherial solution of 


211 


Fermentation - - - 


313 


Gra\dtation - - - - 


70 


saccharine - 


- 313 


Gravity _ . - - 


79 


vinous - 


313 


Growth of plants - - - 


294 


Felling colliery 


- 178 


Gunpowder - - - 


277 


Fibrin - - - - 


321 


Gypsum - , - - 


271 


Fire damp - - - 


- 177 






Fixed air - 


149 


Hartshorn - - - - 


146 


Fixed oils - . - 


- 311 


Heat . - - - 


11 


Florence Hask - - - 


102 


animal - - - - 


328 


Friction - . . 


- 43 


latent- - - - 


131 


Flowers of sulphur - 


155 


matter of - - - 


11 


zinc 


- 246 


radiation of - - 


28 


Fluidity, caloric of - 


13 


Hydriodate of potash 


171 


Fluoric acid - - - 


- 173 


Hydriodic acid - - - 


171 


Fulminating powder - 


277 


Hydro- nitric acid - - - 


145 


Food of plants 


- 294 


Hydrogen - - - - 


123 


Freezing mixtures 


41 


carburetted 


175 


Fluate of lime 


- 173 


sulphuretted 


187 


Fowler's solution 


251 


phosphuretted - 


189 


Fusible alloy - - - 


- 202 


Hydrosulphurets 


268 


Furnace, lamp - - - 


106 


Hydrosulphuret of otash 


288 



INDEX. 



Ice cream 

Imponderable agents 
Inkj indelible 

sympathetic 
Inorganic chemistry 
Iodides 

Iodine - - - 
Iodic acid 

Iodine and hydrogen 
Iridium 
Iron - - - 

meteoric 

oxides of 

rust of - , 

carburet of 

sulphate of - 

sulphuret of - 

tinned 
Isinglass 
Ittria 

Kelp 

King's yellow 

Lamp, furnace 
flameless 



safety 
Latent heat 
Laws of combination 

of proportion 
Lead - - - - 

oxides of - 

white - - - 

sulphuret of 

poisonous 
Lemons, salt of - 
Liquid ammonia - 

phosphorus 
Light - 

decomposition of 

without heat 

effects of, on colors 

effects of, on crystallization 47 
Light carburetted hydrogen 175 

Lime 229 

chloride of - - - 229 

phosphuret of - - 234 

water - - - 229 

carbonate of - - - 284 
Liquidfj, expand by heat - 27 

conducting powers of 24 
Litharge - - - - 263 
Lithium - - - - 224 
Lunar caustic - . - 278 



40 
10 
278 
258 
115 
170 
169 
170 
171 
216 
242 
243 
243 
243 
244 
274 
245 
248 
322 
238 

286 
251 

106 
213 
181 
13 
86 
88 
262 
263 
263 
264 
265 
304 
147 
161 
44 
44 
45 
47 



Magistery of bismuth 



259 



Magnesia - - - - 


236 


sulphate of 


272 


Manganese - - - 


241 


oxides of - - 


241 


Massicot - - - - 


263 


Matrass - - - - 


100 


Molasses - - - - 


307 


Melting pot - 


100 


Mercury - - - - 


204 


peroxide of - - 


206 


protochloride of 


20C 


sulphuret of - - 


20^ 


Metallic compounds - 


201 


salts 


201 


alloys - - - 


202 


Metals - - - - - 


196 


general properties of 


197 


how reduced 


199 


arrangement of 


203 


combustible 


198 


meteoric iron - 


243 


Mineral green - - - 


261 


Mineral waters - - - 


340 


Mirrors, concave - - - 


21? 


Mixtures - - - - 


85 


Molybdic acid - - - 


253 


Molybdenum - - - 


353 


Mordant - - - - 


310 


Morphia - - - - 


319 


Multiple proportions 


88 


Muriates - - - - 


286 


Muriatic acid - - - 


166 


Musical tones - - - 


125 


Narcotine - - - - 


320 


Nickel - . - . 


258 


Nitrates - - - - 


275 


Nitric acid - - . 


144 


anhydrous - - - 


145 


oxide - - - 


141 


Nitre - - 


276 


Nitrous acid - - - 


143 


oxide - - - 


138 


Nitrogen - - - - 


134 


chloride of - - 


168 


and hydrogen 


146 


Nomenclature . - - 


110 


Non-metallic bodies - 


115 


Oil gas - - - - 


184 


Oil of vitriol - - - .. 


157 


Oils, vegetable - - - 


311 


Olefiant gas - - - - 


182 


Opium - - - - 


319 


Organic chemiatry - 


289 


Orpimcnt - - - - 


251 



INDEX. 



Osmium 


- 


- 210 


Respiration - - - 


- 325 


Oxalates - - - 


- 


301 


Receiver - - - 


101 


Oxides, metallic - 


. 


- 198 


Retort - - - - 


. 101 


Oxidation 


112, 


118, 198 


Rhodium - - - 


215 


Oxygen gas - 




- 115 


Rust of iron - - - 


- 243 


combustion 


in - 


119 






Oxymuriatic acid - 


- 


- 163 


Saccharine fermentation 


- 313 


Oxymuriate of potash 


- 


280 


Safety lamp - ^ 


181 


Oxygenized water 


- 


- 133 


Sal-ammoniac 
Salifiable base - 


- 286 
265 


Palladium 


_ 


- 215 


Salt, common 


- 223 


Pearlash - - - 


_ 


285 


of sorrel 


301 


Phosphates - 


. 


- 282 


of lemons 


- 302 


Phosphate of soda 


- 


282 


Salts 


265 


Phosphoric acid 


- 


- 161 


remarks on - 


- 265 


Phosphorus 


- 


160 


nomenclature 


110 


Phosphorescence - 


- 


- 45 


Sap of plants 


- 296 


Phosphuretted hydrogen - 


189 


Scale of equivalents - 


- 96, 346 


Pile of Volta 




- 57 


Sealing wax - - - 


- 318 


Plants, growth of 




294 


Serum - - - 


323 


Plants, food of 




- 294 


Silica - - 


- 239 


Plaster of Paris 




271 


Silicium - « - 


238 


Platinum 




- 212 


Silver > . . . 


. 208 


sponge 




126 


solvent of - 


208 


protoxide of 




- 215 


Silver tree - - - 


- 209 


peroxide of - 




215 


Silvering powder 


209 


Pneumatic cistern - 




- 131 


Simple bodies 


- 113 


Plumbago - - - 




245 


Smalt 


257 


Ponderable bodies - 


. 


- 112 


Soda - - - - 


- 223 


Potassa - - - 




220 


muriate of - 


223 


Potassium 


- 


- 271 


carbonate of - 


- 285 


oxide of 




220 


Sodium - - - 


221 


Potato starch 


- 


- 308 


protoxide of 


. 222 


Potash, carbonate of - 




285 


chloride of 


223 


Precipitate, red 


- 


- 206 


Solar spectrum 


- 45 


Proportions, definite - 


- 


86 


Solids expand by heat 


25 


by volume 


- 


- 91 


Solution - - - 


- 77 


how ascertained 


95 


Sources af caloric 


43 


Prussic acid - 


- 


- 191 


Spar, Derbyshire - 


- 284 


Pyrites - 


» 


245 


heavy 


270 


Pyrometer 


- 


- 25 


Specific gravity 
of solids 


- 106 
107 


Cluaniity of matter - 


- 


- 77 


of liquids - 


- 108 


Cluicklime 


- 


228 


of gases 


109 


Quicksilver - 


. 


- 204 


Spirituous liquors - 


- 316 


Cluinia - - - 


- 


321 


Sponge, platina 


126 


sulphate of - 


- 


- 321 


Starch - - - - 
Steam - - - 


. 308 
15 


Radiant heat - 


- 


- 28 


latent heat of 


- 16 


Realger - - - 


. 


251 


Steel - 


244 


Red oxide of copper 


_ 


- 261 


Strontia - - - 


- 227 


lead - - - 


- 


264 


Sugar, how made 


307 


precipitate 


- 


- 206 


of lead 


- 300 


Reduction of metals - 


- 


199 


Sulphates 


269 


Reflectors 


. 


- 29 


Sulphate of potash 


- 269 


Resins - , - 


- 


312 


of soda 


QTO 





INDEX. 






Sulphate of baryta 


- 270 Vapor 




19 


of lime 


271 ' Van Helmont's willow - 




294 


of magnesia - 


- 272, Vegetation - - . 




291 


of Eilumnia - 


273 ; VecTctable acids 




299 


of iron - 


- 274 


alkalies 




318 


of zinc 


275 


chemistry 




291 


Sulphur - - - 


- 154 


analysis 




291 


Sulphurets - - - 


201 


ingredients of - 




306 


Sulphuret of lead, - 


- 264 


Verdigris - - - - 




301 


of arsenic 


251 


Verditer - - - 




261 


of antimony - 


- 255 


Vermilion - - - 




208 


of iron 


245 


Vinegar - - - 




299 


of copper 


- 195 


Vinous fermentation - 




313 


of carbon - 


296 


Vitriol, green 




274 


Sulphurous acid - 


- 155 


white - - - 




275 


Sulphuric acid - - - 


157 


Volumes, theory of 


- 


91 


Sulphuretted hydrogen - 


- 187 


Volta'spile 




57 


Sup][)orters of combustion - 


113 


Volatile salt - 


- 


147 


Synthesis - - - 


9,127 












Water, decomposition of 63, 82, 122 


Tannin - - - 


- 310 


composition of - 


- 


128 


Tapioca - - - - 


308 


properties of - 




131 


Tartar emetic 


- 203 


oxygenized 


- 


133 


Tartar, cream of - - 


302 


weight of - - 




132 


Tartaric Eicid 


- 302 


expands in freezing 


- 


132 


Telluriur.1- 


260 


of crystallization - 




267 


Temperature, animal 


22,328 


boiling temperature ( 


)f 


17 


Theory of atoms - 


- 98 


analysis of - 


63 


,335 


Thermometer - - . 


35 


synthesis of .^ - 


- 


127 


differential - 


- 36 








air 


36 


Wheat flour - 


. 


309 


construction of 


- 37 


White arsenic - - - 




250 


Tin - - 


248 


Wollaston's scale - 


96, 346 


Titanium - - - 


- 260 


Wolfram - - . - 




253 


Tones, musical - - - 


125 








Trough, galvanic - 


- 59 


Zinc - - - - 




246 


Tungsten - - - - 


253 


oxide of - - 


- 


246 


Tungstic acid 


- 254 


flowers of - 




246 


Turpentine, oil of - - 


313 


alloy of - 
Zaffree - - - . 


- 


246 
257 


Uranium ... 


- 256 


Zirconia - - - 


. 


238 


Vacuum, boiling in 


- 17 


Zero 




39 



INDEX TO PARTS V. & VI. 



Acid, meconic - - 

tannic, - - - 
Alkaloids, - . _ _ 

Alcohol, - - . - 

in wines, ... 
Analysis of ores, 

of vegetables, 
Antimony, analysis of 
Arsenic, tests of - - - 
Bismuth, analysis of - 
Caffein, - - - - 

Calico printing, - _ - 
Carbo-Sulphiiric acid, - 
Chlorine and sulphur, 
Chrome, assay of - - 

Cinnabar, _ - - _ 

Cobalt, analysis of - - 
Coffee, ----- 
Codeia, - - - - - 
Copper, tests for - 

reduction of - 
Cupellation, _ - - 

Dyeing, art of - 
Diamond, burning of - 

Elatin, 

Extractive, - - - - 
Gentianin, - - - - 
Gold, analysis of - 
Hydracids, - - - - 
Hydrobromic acid, 
Hydrochloric, - - - 
Hydriodic, - - - - 
Hydrofluoric, - - - - 
Hydroselenic, - - - 
Hydrosulphuric, - - - 
Hydrocyanic, - _ - 
H ydroferrocy anic, 
Hypo, meaning of 
Hydrogen, decomposition by - 
Ink, 



417 
411 
415 

391 
392 
350 
404 
363 
357 
3611 
420; 
414 
404! 
3991 
379 1 
356 
359! 
417: 
415; 
367| 
369 
347 
413 
400 
421 
409 
418 
351 
394 



395 
395 
397 
412 



Iron, test of - 

assay of - 

reduction of - - 
Lead, analysis of - - 
Magnet, - - _ - 
Manganese, assay of 
Meonia, _ - _ - 
Meconic acid, - - - 
Mineralogy, Chemical - 
Molybdena, tests for 
Morphia, _ - - - 
Muffle, - - - - 
Narceia, - - - _ 
Oxygen and Hydrogen, 
Platinum, assay of - 

malleable, - - - 
Reduction, what 
Roasting ores, - - - 
Salts of Hydracids, - 
Silver, analysis of - 

antimonial, 

muriate of - - 
Sulphuret of Carbon, 
Sugar, - - - - 

beet, - - - - 

maple, - - - 
Tannic acid, - - - 
Tannin, _ - _ . 

quantity of - 
Tin, assay of - - - 
Thebaia, - - - - 
Uranium, analysis of - 
Vanadium, - - - 
Vanadiates, - - - 

Vegetables, analysis of - 

ultimate principles of 

alkaloids, 
Wine, - - - - 
Zinc, analysis of - - 

reduction of - 



37 
37 
37< 

36- 
34- 

38( 
411 
41 
34- 

38( 

41; 

34i 
41( 
39; 
38: 
38^ 
341 
34' 
39i 
35: 
35^ 
35^ 

4o: 

42< 
42( 
42( 
411 
40i 
4V 
37( 
41( 
38] 
381 
38J 
40^ 
40( 
4i; 
39( 
37 
37^ 



U^^^^ 



£:riK]i»:;Si 



LIBRARY OF CX)NGRESS 




003 833 305 7 • 



